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Sample records for alginate gel polymer

  1. Cd(II) Speciation in alginate gels

    NARCIS (Netherlands)

    Davis, T.A.; Kalis, E.J.J.; Pinheiro, J.P.; Town, R.M.; Leeuwen, van H.P.

    2008-01-01

    Polysaccharides, such as those occurring in cell walls and biofilms, play an important role in metal speciation in natural aqueous systems. This work describes the speciation of Cd(II) in alginate gels chosen as a model system for biogels. The gels are formed by bridging calcium ions at junction zon

  2. Understanding Alginate Gel Development for Bioclogging and Biogeophysical Experiments

    Science.gov (United States)

    Brown, I.; Atekwana, E. A.; Abdel Aal, G. Z.; Atekwana, E. A.; Sarkisova, S.; Patrauchan, M.

    2012-12-01

    Bioremediation strategies to mitigate the transport of heavy metals and radionuclides in subsurface sediments have largely targeted to increase the mobility and/or solubility of these compounds by the stimulation of biogeochemical activity of the metal- and sulfate-reducing bacteria. The latter secrete and/or release out diverse biochemical molecule including, first of all, organic acids and biopolymers such as alginic acid, proteins and DNA. Alginate gel is one of the major components determining the structure of biofilm which causes clogging in porous media. Biopolymers composing biofilm having, at least, two main functions: to be a scaffold for a microbial biofilm, and to regulate the exchange of metabolites and ions between an environment and bacterial cells. Additionally, the accumulation of biopolymers and a matured biofilm within porous media was shown to contribute to a detectable biogeophysical signal, spectral induced polarization (SIP), in particular. Our objective is to understand the role of different biofilm components on the SIP response as the latter has been proposed as a non-invasive tool to monitor biofilm development and rate of clogging in the subsurface. Understanding the process of alginate gel development may aid in the understanding of the fate and transport of mineralized heavy metals and radionuclides in contaminated soils. Here we describe the reciprocal relationship between environmental chemistry and alginate gel development. Commercial (Sigma) alginic acid (AA) was used as a substratum for the preparation of a model gel. AA was solubilized by adjusting solutions with pH up to 4 with 0.1 NaOH. Both Ca(OH)2 or CaCl2 were used to initiate the gelation of alginate. pH, fluid conductivity, soluble Ca2+ concentration, and a yield of gelated alginate were monitored in both liquid and porous media after the interaction of calcium compounds with alginate. This study confirms the critical role of Ca2+ for alginate gelation, biofilm development

  3. Active Polymer Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2010-01-01

    Full Text Available Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of heart muscles. Here we show a novel biomimetic gel actuator that can walk spontaneously with a wormlike motion without switching of external stimuli. The self-oscillating motion is produced by dissipating chemical energy of oscillating reaction. Although the gel is completely composed of synthetic polymer, it shows autonomous motion as if it were alive.

  4. Active Polymer Gel Actuators

    OpenAIRE

    Shuji Hashimoto; Ryo Yoshida; Yusuke Hara; Shingo Maeda

    2010-01-01

    Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of he...

  5. Preparation of novel silica-coated alginate gel beads for efficient encapsulation of yeast alcohol dehydrogenase.

    Science.gov (United States)

    Xu, Song-Wei; Lu, Yang; Li, Jian; Zhang, Yu-Fei; Jiang, Zhong-Yi

    2007-01-01

    Biomimetic formation has undoubtedly inspired the preparation of novel organic-inorganic hybrid composites. In this study, silica-coated alginate gel beads were prepared by coating the surface of alginate gel beads with silica film derived from tetramethoxysilane (TMOS). The composition and structure of the silica film were characterized by FT-IR and SEM equipped with EDX. The swelling behavior of silica-coated alginate gel beads was studied to be more stable against swelling than that of alginate gel beads. The results showed that silica-coated alginate gel beads exhibited appropriate diffusion property. The effective diffusion coefficient (D(e)) of NADH in silica-coated alginate beads was 1.76 x 10(-10) m2/s, while the effective diffusion coefficient in alginate beads was 1.84 x 10(-10) m2/s. The model enzyme yeast alcohol dehydrogenase (YADH) was encapsulated in silica-coated alginate and pure alginate beads, respectively. Enzyme leakage of YADH in alginate gel beads was determined to be 32%, while the enzyme leakage in silica-coated alginate gel beads was as low as 11%. Furthermore, the relative activity of YADH in alginate gel beads decreased almost to zero after 10 recycles, while the relative activity of YADH in silica-coated alginate gel beads was 81.3%. The recycling stability of YADH in silica-coated alginate gel beads was found to be increased significantly mainly due to the effective inhibition of enzyme leakage by compact silica film.

  6. Kefiran-alginate gel microspheres for oral delivery of ciprofloxacin.

    Science.gov (United States)

    Blandón, Lina M; Islan, German A; Castro, Guillermo R; Noseda, Miguel D; Thomaz-Soccol, Vanete; Soccol, Carlos R

    2016-09-01

    Ciprofloxacin is a broad-spectrum antibiotic associated with gastric and intestinal side effects after extended oral administration. Alginate is a biopolymer commonly employed in gel synthesis by ionotropic gelation, but unstable in the presence of biological metal-chelating compounds and/or under dried conditions. Kefiran is a microbial biopolymer able to form gels with the advantage of displaying antimicrobial activity. In the present study, kefiran-alginate gel microspheres were developed to encapsulate ciprofloxacin for antimicrobial controlled release and enhanced bactericidal effect against common pathogens. Scanning electron microscopy (SEM) analysis of the hybrid gel microspheres showed a spherical structure with a smoother surface compared to alginate gel matrices. In vitro release of ciprofloxacin from kefiran-alginate microspheres was less than 3.0% and 5.0% at pH 1.2 (stomach), and 5.0% and 25.0% at pH 7.4 (intestine) in 3 and 21h, respectively. Fourier transform infrared spectroscopy (FTIR) of ciprofloxacin-kefiran showed the displacement of typical bands of ciprofloxacin and kefiran, suggesting a cooperative interaction by hydrogen bridges between both molecules. Additionally, the thermal analysis of ciprofloxacin-kefiran showed a protective effect of the biopolymer against ciprofloxacin degradation at high temperatures. Finally, antimicrobial assays of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhymurium, and Staphylococcus aureus demonstrated the synergic effect between ciprofloxacin and kefiran against the tested microorganisms. PMID:27289312

  7. Characterization of Sulfated Alginate Hybrid Gels for Tissue Engineering

    OpenAIRE

    Aaen, Ragnhild

    2015-01-01

    Tissue engineering is a field aiming to replace damaged tissue while reducing the great need of organ donors the world is facing today. Alginates are linear co-polymers consisting of the two monosaccharides β-D-mannuronic acid (M), and its 5-epimer α-L-guluronic acid (G). They can form hydrogels, and are candidates for use in tissue engineering scaffolds. Alginate is readily available at a low cost, and its hydrogels meet requirements of scaffolds such as mechanical strength and good biocomp...

  8. Effects of Alginate Gel on Rheological Properties of Hair-tail( Trichiurus lepturus) Surimi

    Institute of Scientific and Technical Information of China (English)

    XUE Yong; LIU Xin; ZHANG Lili; LIN Dan; XU Jiachao; XUE Changhu

    2011-01-01

    Effects of alginate gel at different concentrations on rheological properties of hair-tail (Trichiurus lepturus) surimi were investigated. Alginate gel (1%-3%) exhibited enhanced effects, especially when alginate gel concentration increased. The rheologicai properties of mixture samples were studied by the time sweep, frequency sweep and temperature sweep. The critical strain values of the mixture samples for the onset of non-linear viscoelasticity were about 5%. The storage modulus G' of the mixture samples increased with time for 4 h. The frequency sweep showed that G' was greater than G" for all the mixture gels with different alginate gel concentrations, and values of both n' and n" for all samples were low (<0.2), these constants corresponding to G' and G", and indicating the elasticity of mixture gels. The values of storage modulus G' decreased during heating process and increased with decreasing temperature.

  9. Topical Review: Polymer gel dosimetry

    OpenAIRE

    Baldock, C; De Deene, Y; Doran, S.; Ibbott, G; Jirasek, A.; Lepage, M.; McAuley, K B; Oldham, M; Schreiner, L J

    2010-01-01

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose ...

  10. 3-dimensional polymer gel dosimetry

    International Nuclear Information System (INIS)

    Recently developed techniques in conformal radiotherapy demand special properties of radiation dosimeters. Polymer gel dosimeter evaluated by nuclear magnetic resonance (NMR) is promising tool which can be used for measuring rather complicated 3-dimensional dose distributions with required precision of ± 5 %. This system is based on radiation-induced polymerisation and cross-linking of acrylic monomers which are uniformly dispersed in aqueous gel. The formation of cross-linked polymers in the irradiated regions of the gel increases the NMR relaxation rates of neighbouring water protons. BANG-2 type polymer gel was prepared. The composition of gel dosimeter was as follows: 3 % N,N'-methylene-bisacrylamide, 3 % acrylic acid, 1 % sodium hydroxide, 5 % gelatine, and 88 % water, where all percentages are by weight. The dosimeters in glass vessels were homogeneously irradiated by 60Co gamma photons in a Gammacell 220 unit and by 4 MV, 6 MV and 18 MV X ray photons on Varian Clinac 600C and 2100 C linear accelerators by doses in the range of 0-50 Gy. Evaluation of dosimeters was performed on Siemens EXPERT 1 T and Siemens VISION 1,5 T scanners. Multi-echo CPMG sequence with 16 echoes was used for the evaluation of T2-relaxation times in irradiated gel dosimeters. The dependence of 1/T2 response of dosimeters was studied on following factors: absorbed dose, energy of applied radiation, temperature during NMR evaluation, time since irradiation to NMR evaluation and strength of the magnetic field. An exponential dependence of 1/T2 response on absorbed dose in the range of 0-50 Gy was observed, in the range 0-10 Gy the data could be fitted by a linear function. There was observed no dependence of 1/T2 response on: energy (for three different photon energies used in this study), strength of magnetic field of NMR scanner, time from irradiation of the dosimeters to NMR evaluation. Increase of gel dosimeter 1/T2 response with the decrease of the temperature during NMR evaluation

  11. Water equivalence of polymer gel dosimeters

    International Nuclear Information System (INIS)

    To evaluate the water equivalence and radiation transport properties of polymer gel dosimeters over the wide range of photon and electron energies 14 different types of polymer gels were considered. Their water equivalence was evaluated in terms of effective atomic number (Zeff), electron density (ρe), photon mass attenuation coefficient (μ/ρ), photon mass energy absorption coefficient (μen/ρ) and total stopping power (S/ρ)tot of electrons using the XCOM and the ESTAR database. The study showed that the effective atomic number of polymer gels were very close (en/ρ for all polymer gels were in close agreement (tot of electrons in polymer gel dosimeters were within 1% agreement with that of water. From the study we conclude that at lower energy (<80keV) the polymer gel dosimeters cannot be considered water equivalent and study has to be carried out before using the polymer gel for clinical application

  12. Novel alginate matrix for tissue engineering: selective substitution ofmannuronic acid residues in alginate with bioactive peptides and the use of these polymers as scaffolds for cells

    OpenAIRE

    Karstensen, Kristin

    2010-01-01

    Alginate is a naturally occurring biopolymer that forms gels in the presence of divalent ions.It is a polysaccharide which functions as a structural component in marine brown algae and some bacteria. Alginate forms hydrogels by ionic cross-linking at very mild (physiological) conditions allowing immobilization in alginate to be carried out at cell suitable conditions.By entrapping therapeutic cells in alginate gels they can be protected from the host immune system upon transplantation, render...

  13. Composite alginate gels for tunable cellular microenvironment mechanics

    Science.gov (United States)

    Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

    2016-01-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4–12 kPa) as compared to healthy tissue (E = 0.4–2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation. PMID:27484403

  14. Composite alginate gels for tunable cellular microenvironment mechanics

    Science.gov (United States)

    Khavari, Adele; Nydén, Magnus; Weitz, David A.; Ehrlicher, Allen J.

    2016-08-01

    The mechanics of the cellular microenvironment can be as critical as biochemistry in directing cell behavior. Many commonly utilized materials derived from extra-cellular-matrix create excellent scaffolds for cell growth, however, evaluating the relative mechanical and biochemical effects independently in 3D environments has been difficult in frequently used biopolymer matrices. Here we present 3D sodium alginate hydrogel microenvironments over a physiological range of stiffness (E = 1.85 to 5.29 kPa), with and without RGD binding sites or collagen fibers. We use confocal microscopy to measure the growth of multi-cellular aggregates (MCAs), of increasing metastatic potential in different elastic moduli of hydrogels, with and without binding factors. We find that the hydrogel stiffness regulates the growth and morphology of these cell clusters; MCAs grow larger and faster in the more rigid environments similar to cancerous breast tissue (E = 4–12 kPa) as compared to healthy tissue (E = 0.4–2 kpa). Adding binding factors from collagen and RGD peptides increases growth rates, and change maximum MCA sizes. These findings demonstrate the utility of these independently tunable mechanical/biochemistry gels, and that mechanical confinement in stiffer microenvironments may increase cell proliferation.

  15. HPMC-based gastroretentive dual working matrices coated with Ca(+2) ion crosslinked alginate-fenugreek gum gel membrane.

    Science.gov (United States)

    Bera, Hriday; Gaini, Chakravarthy; Kumar, Sanoj; Sarkar, Srimanta; Boddupalli, Shashank; Ippagunta, Sohitha Reddy

    2016-10-01

    Novel alginate-fenugreek gum (FG) gel membrane coated hydroxypropylmethylcellulose (HPMC) based matrix tablets were developed for intragastric quetiapine fumarate (QF) delivery by combining floating and swelling mechanisms. The effects of polymer blend ratios [HPMC K4M:HPMC E15] and citric acid contents on time taken for 50% drug release (t50%, min) and drug release at 8h (Q8h, %) were studied to optimize the core tablets by 3(2) factorial design. The optimized tablets (F-O) exhibited t50% of 247.67±3.51min and Q8h of 71.11±0.32% with minimum errors in prediction. The optimized tablets were coated with Ca(+2) ions crosslinked alginate-FG gel membrane by diffusion-controlled interfacial complexation technique. The biopolymeric-coated optimized matrices exhibited superior buoyancy, preferred swelling characteristics and slower drug release rate. The drug release profiles of the QF-loaded uncoated and coated optimized matrices were best fitted in Korsmeyer-Peppas model with anomalous diffusion driven mechanism. The uncoated and coated tablets containing QF were also characterized for drug-excipients compatibility, thermal behaviour and surface morphology by FTIR, DSC and SEM analyses, respectively. Thus, the newly developed alginate-FG gel membrane coated HPMC matrices are appropriate for intragastric delivery of QF over a prolonged period of time with greater therapeutic benefits. PMID:27287111

  16. HPMC-based gastroretentive dual working matrices coated with Ca(+2) ion crosslinked alginate-fenugreek gum gel membrane.

    Science.gov (United States)

    Bera, Hriday; Gaini, Chakravarthy; Kumar, Sanoj; Sarkar, Srimanta; Boddupalli, Shashank; Ippagunta, Sohitha Reddy

    2016-10-01

    Novel alginate-fenugreek gum (FG) gel membrane coated hydroxypropylmethylcellulose (HPMC) based matrix tablets were developed for intragastric quetiapine fumarate (QF) delivery by combining floating and swelling mechanisms. The effects of polymer blend ratios [HPMC K4M:HPMC E15] and citric acid contents on time taken for 50% drug release (t50%, min) and drug release at 8h (Q8h, %) were studied to optimize the core tablets by 3(2) factorial design. The optimized tablets (F-O) exhibited t50% of 247.67±3.51min and Q8h of 71.11±0.32% with minimum errors in prediction. The optimized tablets were coated with Ca(+2) ions crosslinked alginate-FG gel membrane by diffusion-controlled interfacial complexation technique. The biopolymeric-coated optimized matrices exhibited superior buoyancy, preferred swelling characteristics and slower drug release rate. The drug release profiles of the QF-loaded uncoated and coated optimized matrices were best fitted in Korsmeyer-Peppas model with anomalous diffusion driven mechanism. The uncoated and coated tablets containing QF were also characterized for drug-excipients compatibility, thermal behaviour and surface morphology by FTIR, DSC and SEM analyses, respectively. Thus, the newly developed alginate-FG gel membrane coated HPMC matrices are appropriate for intragastric delivery of QF over a prolonged period of time with greater therapeutic benefits.

  17. Decolourisation of dyes under electro-Fenton process using Fe alginate gel beads

    International Nuclear Information System (INIS)

    Highlights: ► Catalytic activity of Fe alginate gel beads for the remediation of wastewater was tested. ► New electro-Fenton process for the remediation of polluted wastewater. ► Continuous dye treatment without operational problem with high removal. - Abstract: This study focuses on the application of electro-Fenton technique by use of catalytic activity of Fe alginate gel beads for the remediation of wastewater contaminated with synthetic dyes. The Fe alginate gel beads were evaluated for decolourisation of two typical dyes, Lissamine Green B and Azure B under electro-Fenton process. After characterization of Fe alginate gel beads, the pH effect on the process with Fe alginate beads and a comparative study of the electro-Fenton process with free Fe and Fe alginate bead was done. The results showed that the use of Fe alginate beads increases the efficiency of the process; moreover the developed particles show a physical integrity in a wide range of pH (2–8). Around 98–100% of dye decolourisation was obtained for both dyes by electro-Fenton process in successive batches. Therefore, the process was performed with Fe alginate beads in a bubble continuous reactor. High color removal (87–98%) was attained for both dyes operating at a residence time of 30 min, without operational problems and maintaining particle shapes throughout the oxidation process. Consequently, the stable performance of Fe alginate beads opens promising perspectives for fast and economical treatment of wastewater polluted by dyes or similar organic contaminants.

  18. Conductivity behaviour of polymer gel electrolytes: Role of polymer

    Indian Academy of Sciences (India)

    S S Sekhon

    2003-04-01

    Polymer is an important constituent of polymer gel electrolytes along with salt and solvent. The salt provides ions for conduction and the solvent helps in the dissolution of the salt and also provides the medium for ion conduction. Although the polymer added provides mechanical stability to the electrolytes yet its effect on the conductivity behaviour of gel electrolytes as well as the interaction of polymer with salt and solvent has not been conclusively established. The conductivity of lithium ion conducting polymer gel electrolytes decreases with the addition of polymer whereas in the case of proton conducting polymer gel electrolytes an increase in conductivity has been observed with polymer addition. This has been explained to be due to the role of polymer in increasing viscosity and carrier concentration in these gel electrolytes.

  19. Controlled antiseptic release by alginate polymer films and beads.

    Science.gov (United States)

    Liakos, Ioannis; Rizzello, Loris; Bayer, Ilker S; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia

    2013-01-30

    Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca(2+)-cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants.

  20. Preparation, Properties and Mechanism of Inhomogeneous Calcium Alginate Ion Cross-linking Gel Microspheres

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Inhomogeneous calcium alginate ion cross-linking gel microspheres, a novel ion absorbent, were prepared by dropping a sodium alginate solution to a calcium chloride solution via an electronic droplet generator. Calcium alginate microspheres have uniform particle sizes, a smooth surface and a microporous structure. The electrode probe reveals the inhomogeneous distribution of calcium ions with the highest concentration on the surface, and the lowest concentration in the cores of the spheres. As a novel ion adsorbent, calcium alginate gel microspheres have a lower limiting adsorption mass concentration, a higher enrichment capacity and a higher adsorption capacity for Pb2+ than usual ion exchange resins. The highest percentage of the adsorption is 99.79%. The limiting adsorption mass concentration is 0.0426 mg/L. The adsorption capacity for Pb2+ is 644 mg/g. Calcium alginate gel microspheres have a much faster ion exchange velocity than D418 chelating resin and D113 polyacrylate resin. The moving boundary model was employed to interpret the ion exchange kinetics process, which indicates that the ion exchange process is controlled by intraparticle diffusion of adsorbable ions. So the formation of inhomogeneous gel microspheres reduces the diffusion distance of adsorbable ions within the spheres and enhances the ion exchange velocity. Alginate has a higher selectivity for Pb2+ than for Ca2+ and the selectivity coefficient KPbCa is 316. As an ion cross-linking gel, calcium alginate inhomogeneous microspheres can effectively adsorb heavy metal Pb2+ at a higher selectivity and a higher adsorption velocity. It is a novel and good ion adsorbent.

  1. Fundamental Characteristics of Bioprint on Calcium Alginate Gel

    Science.gov (United States)

    Umezu, Shinjiro; Hatta, Tatsuru; Ohmori, Hitoshi

    2013-05-01

    The goal of this study is to fabricate precision three-dimensional (3D) biodevices those are micro fluidics and artificial organs utilizing digital fabrication. Digital fabrication is fabrication method utilizing inkjet technologies. Electrostatic inkjet is one of the inkjet technologies. The electrostatic inkjet method has following two merits; those are high resolution to print and ability to eject highly viscous liquid. These characteristics are suitable to print biomaterials precisely. We are now applying for bioprint. In this paper, the electrostatic inkjet method is applied for fabrication of 3D biodevices that has cave like blood vessel. When aqueous solution of sodium alginate is printed to aqueous solution of calcium chloride, calcium alginate is produced. 3D biodevices are fabricated in case that calcium alginate is piled.

  2. Pseudomonas aeruginosa AlgG is a polymer level alginate C5-mannuronan epimerase.

    OpenAIRE

    Franklin, M J; Chitnis, C E; Gacesa, P; Sonesson, A; White, D. C.; Ohman, D E

    1994-01-01

    Alginate is a viscous extracellular polymer produced by mucoid strains of Pseudomonas aeruginosa that cause chronic pulmonary infections in patients with cystic fibrosis. Alginate is polymerized from GDP-mannuronate to a linear polymer of beta-1-4-linked residues of D-mannuronate and its C5-epimer, L-guluronate. We previously identified a gene called algG in the alginate biosynthetic operon that is required for incorporation of L-guluronate residues into alginate. In this study, we tested the...

  3. Hybrid Materials of Polymer Gels with Surfactants

    Institute of Scientific and Technical Information of China (English)

    Hu Yan; Kaoru Tsujii

    2005-01-01

    @@ 1 Introduction Polymer gels have been extensively studied[1~17] since the discovery of volume phase-transition of a gel by Tanaka[1~5]. As a unique soft material, gels attract much attention and are tried to be applied for drug-delivery systgems[6], actuators or chemo-mechanical devices[7~9] and so on. In particular, controlled-release of small molecules from a gel is now a subject of special interest[10].

  4. Water equivalence of polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Sellakumar, P. [Bangalore Institute of Oncology, 44-45/2, II Cross, RRMR Extension, Bangalore-560 027 (India)]. E-mail: psellakumar@rediffmail.com; James Jebaseelan Samuel, E. [School of Science and Humanities, Vellore Institute of Technology, Vellore-632 014 (India); Supe, Sanjay S. [Kidwai Memorial Institute of Oncology, Hosur Road, Bangalore-560 027 (India)

    2007-07-15

    To evaluate the water equivalence and radiation transport properties of polymer gel dosimeters over the wide range of photon and electron energies 14 different types of polymer gels were considered. Their water equivalence was evaluated in terms of effective atomic number (Z{sub eff}), electron density ({rho}{sub e}), photon mass attenuation coefficient ({mu}/{rho}), photon mass energy absorption coefficient ({mu}{sub en}/{rho}) and total stopping power (S/{rho}){sub tot} of electrons using the XCOM and the ESTAR database. The study showed that the effective atomic number of polymer gels were very close (<1%) to that of water except PAGAT, MAGAT and NIPAM which had the variation of 3%, 2% and 3%, respectively. The value of {mu}/{rho} and {mu}{sub en}/{rho} for all polymer gels were in close agreement (<1%) with that of water beyond 80keV. The value of (S/{rho}){sub tot} of electrons in polymer gel dosimeters were within 1% agreement with that of water. From the study we conclude that at lower energy (<80keV) the polymer gel dosimeters cannot be considered water equivalent and study has to be carried out before using the polymer gel for clinical application.

  5. Coordination Polymer Gels by Electron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Ha; Cho, Young Je; Jung, Jong Hwa [Gyeongsang National Univ., Jinju (Korea, Republic of)

    2011-07-01

    Hydrogenation of a pyridine derivative possessing tetrazole moieties as end groups, without long alkyl chain groups, results in the formation of a Mg(NO{sub 3}){sub 2} coordination polymer gel. The polymer exhibits a strong fluorescence enhancement upon gel formation. 1 can also be gloated with a variety of magnesium anions such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, Br{sup -} and I{sup -}, indicating that the coordination polymer gel formation of 1 does not strongly depends on anions. The Seam and ABM images of Mg{sup 2+} coordination polymer gel 1 display a flabbier network with several micrometers long, widths in the range 60-70 nm and thicknesses of about 3 nm. In addition, photophysical studies show that the hydrogel exhibits a typical {pi}-{pi} transition and gives rise to high fluorescence behavior. The coordination polymer hydrogel exhibits viscoelastic behavior as evidenced from the rheological studies.

  6. Mussel-inspired alginate gel promoting the osteogenic differentiation of mesenchymal stem cells and anti-infection.

    Science.gov (United States)

    Zhang, Shiwen; Xu, Kaige; Darabi, Mohammad Ali; Yuan, Quan; Xing, Malcolm

    2016-12-01

    Alginate hydrogels have been used in cell encapsulation for many years but a prevalent issue with pure alginates is that they are unable to provide enough bioactive properties to interact with mammalian cells. This paper discusses the modification of alginate with mussel-inspired dopamine for cell loading and anti-infection. Mouse bone marrow stem cells were immobilized into alginate and alginate-dopamine beads and fibers. Through live-dead and MTT assay, alginates modified by dopamine promoted cell viability and proliferation. In vitro cell differentiation results showed that such an alginate-dopamine gel can promote the osteogenic differentiation of mesenchymal stem cell after PCR and ALP assays. In addition to that, the adhesive prosperities of dopamine allowed for coating the surface of alginate-dopamine gel with silver nanoparticles, which provided the gel with significant antibacterial characteristics. Overall, these results demonstrate that a dopamine-modified alginate gel can be a great tool for cell encapsulation to promote cell proliferation and can be applied to bone regeneration, especially in contaminated bone defects. PMID:27612740

  7. Electrochemical Study of Conductive Gel Polymer

    Institute of Scientific and Technical Information of China (English)

    Zhaohui Li; Jing Jiang; Gangtie Lei

    2005-01-01

    @@ 1Introduction Conventional ion-conducting polymer consists of electrolyte salt and polymer matrix, so-called salt-inpolymer. It possesses lower conductivity because the migration of ions depends on the motion of polymer segmental. To increase the ionic conductivity, a kind of gel polymer film (GPF) was prepared by in situ polymerization of methyl methacrylate (MMA) monomer in room-temperature ionic liquid(RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6). Due to immeasurably low vapor pressure, high ionic conductivity, and greater thermal and electrochemical stability, BMIPF6 is suitable electrolyte salts for ion-conducting polymer.

  8. Alginate/Poly(γ-glutamic Acid Base Biocompatible Gel for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Wing P. Chan

    2015-01-01

    Full Text Available A technique for synthesizing biocompatible hydrogels by cross-linking calcium-form poly(γ-glutamic acid, alginate sodium, and Pluronic F-127 was created, in which alginate can be cross-linked by Ca2+ from Ca–γ-PGA directly and γ-PGA molecules introduced into the alginate matrix to provide pH sensitivity and hemostasis. Mechanical properties, swelling behavior, and blood compatibility were investigated for each hydrogel compared with alginate and for γ-PGA hydrogel with the sodium form only. Adding F-127 improves mechanical properties efficiently and influences the temperature-sensitive swelling of the hydrogels but also has a minor effect on pH-sensitive swelling and promotes anticoagulation. MG-63 cells were used to test biocompatibility. Gelation occurred gradually through change in the elastic modulus as the release of calcium ions increased over time and caused ionic cross-linking, which promotes the elasticity of gel. In addition, the growth of MG-63 cells in the gel reflected nontoxicity. These results showed that this biocompatible scaffold has potential for application in bone materials.

  9. Conducting polymer electrodes for gel electrophoresis.

    Directory of Open Access Journals (Sweden)

    Katarina Bengtsson

    Full Text Available In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene (PEDOT can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

  10. Mechanical properties of C-5 epimerized alginates.

    Science.gov (United States)

    Mørch, Y A; Holtan, S; Donati, I; Strand, B L; Skjåk-Braek, G

    2008-09-01

    There is an increased need for alginate materials with both enhanced and controllable mechanical properties in the fields of food, pharmaceutical and specialty applications. In the present work, well-characterized algal polymers and mannuronan were enzymatically modified using C-5 epimerases converting mannuronic acid residues to guluronic acid in the polymer chain. Composition and sequential structure of controls and epimerized alginates were analyzed by (1)H NMR spectroscopy. Mechanical properties of Ca-alginate gels were further examined giving Young's modulus, syneresis, rupture strength, and elasticity of the gels. Both mechanical strength and elasticity of hydrogels could be improved and manipulated by epimerization. In particular, alternating sequences were found to play an important role for the final mechanical properties of alginate gels, and interestingly, a pure polyalternating sample resulted in gels with extremely high syneresis and rupture strength. In conclusion, enzymatic modification was shown to be a valuable tool in modifying the mechanical properties of alginates in a highly specific manner.

  11. Alginate and DNA gels are suitable delivery systems for diabetic wound healing

    OpenAIRE

    Tellechea, A; Silva, EA; Min, J.; Leal, EC; Auster, ME; Pradhan-Nabzdyk, L; Shih, W; Mooney, DJ; Veves, A

    2015-01-01

    © The Author(s) 2014. Diabetic foot ulcers (DFU) represent a severe health problem and an unmet clinical challenge. In this study, we tested the efficacy of novel biomaterials in improving wound healing in mouse models of diabetes mellitus (DM). The biomaterials are composed of alginate- and deoxyribonucleic acid (DNA)-based gels that allow incorporation of effector cells, such as outgrowth endothelial cells (OEC), and provide sustained release of bioactive factors, such as neuropeptides and ...

  12. Dynamic Scaling of Polymer Gels Comprising Nanoparticles

    OpenAIRE

    Teixeira, Alvaro V. N. C.; Geissler, Erik; Licinio, Pedro

    2014-01-01

    We present dynamic light scattering (DLS) measurements of soft polymethyl-methacrylate (PMMA) and polyacrylamide(PA) polymer gels prepared with trapped bodies (latex spheres or maghemite nanoparticles). We show that the anomalous diffusivity of the trapped particles can be analyzed in terms of a fractal Gaussian network gel model for the entire time range probed by DLS technique. This model is a generalization of the Rouse model for linear chains extended for structures with power law network...

  13. Rheological properties of polymer micro-gel dispersions

    Institute of Scientific and Technical Information of China (English)

    Dong Zhaoxia; Li Yahua; Lin Meiqin; Li Mingyuan

    2009-01-01

    The influence of swelling time, temperature, NaCI concentration and polymer micro-gel concentration on rheological properties of polymer micro-gel dispersions was studied by using a HAAKE rheometer. The results showed that with increasing swelling time and NaCI concentration, the polymer micro-gel dispersions changed from a shear-thickening fluid to a Newtonian fluid. The polymer micro- gel dispersion show shear-thinning in non-saline water. At higher swelling temperature, the time of the polymer micro-gel dispersion showing shear-thickening was shorter. With increasing polymer micro-gel concentration, the dispersion changed from shear-thickening to shear-thinning.

  14. Alginate Production from Alternative Carbon Sources and Use of Polymer Based Adsorbent in Heavy Metal Removal

    Directory of Open Access Journals (Sweden)

    Çiğdem Kıvılcımdan Moral

    2016-01-01

    Full Text Available Alginate is a biopolymer composed of mannuronic and guluronic acids. It is harvested from marine brown algae; however, alginate can also be synthesized by some bacterial species, namely, Azotobacter and Pseudomonas. Use of pure carbohydrate sources for bacterial alginate production increases its cost and limits the chance of the polymer in the industrial market. In order to reduce the cost of bacterial alginate production, molasses, maltose, and starch were utilized as alternative low cost carbon sources in this study. Results were promising in the case of molasses with the maximum 4.67 g/L of alginate production. Alginates were rich in mannuronic acid during early fermentation independent of the carbon sources while the highest guluronic acid content was obtained as 68% in the case of maltose. The polymer was then combined with clinoptilolite, which is a natural zeolite, to remove copper from a synthetic wastewater. Alginate-clinoptilolite beads were efficiently adsorbed copper up to 131.6 mg Cu2+/g adsorbent at pH 4.5 according to the Langmuir isotherm model.

  15. In situ coronary stent paving by Pluronic F127-alginate gel blends: Formulation and erosion tests.

    Science.gov (United States)

    Dalmoro, Annalisa; Barba, Anna Angela; Grassi, Mario; Grassi, Gabriele; Lamberti, Gaetano

    2016-07-01

    In this work the development of an experimental protocol to perform the in situ gel-paving of coronary stent is presented. Biocompatible aqueous blends of Pluronic F127 and sodium alginates are used as potential drug dosage system for pharmacological in situ treatment of coronary in-stent restenosis. Pluronic F127/alginate aqueous blend has the unique characteristic to be liquid at room condition and to form gel at physiological temperature. The proposed protocol is based on the blend injection on stent wall previously implanted in a flexible silicon pipe mimicking the coronary artery. Injected blend is warmed up until human body temperature achieving a soft gel, then it is reticulated by copper bivalent ions to obtain an hard gel. To test the gel paving resistance to erosion phenomena when it is exposed to fluid flux (i.e. blood flux) a dedicated device, (the Simulated Artery Device, SAD), was built to simulate the human circulatory apparatus. The SAD is an hydraulic circuit in which a buffer solution (at pH 7.4) was fluxed by a peristaltic pump through the pipe hosting the covered stent. Erosion tests were performed monitoring, by gravimetric and spectrophotometric methods, the residual mass anchored to stent mesh after given times. The obtained results showed that the in situ gel-paving developed protocol was efficacious and reliable. The gel-paving was completely eroded in a time of the same order of magnitude of the physiological period required to restore the coronary lesion (subsequent to the atheroma removal) and of a pharmacological therapy to inhibit the in-stent-restenosis pathology. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1013-1022, 2016. PMID:25997168

  16. The Efficiency of Vascular Embolization Using Alginate Gel : An Experimental Study in Rabbit

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the applicability of poly-L-guluronic alginate (PGA) gel in vascular embolization with angiography simulation. To prepare a gel-forming PGA from no guluronate-rich Laminaria japonica, a new acid hydrolysis method was employed with a lower HCL concentration (0.03 M) and a shorter treatment time (5 min). The obtained PGAs were selected based on gel stability and viscosity. Glass aneurysm model was used to simulate gel embolization in vitro. Then, finally, the PGA was used to embolize the renal vascular system by using a rabbit model and angiography. Glass aneurysm model was made to simulate gel embolization procedure. PGA solution was injected from pump through 2-way catheter. Subsequent injection of CaCl2 successfully formed gels inside aneurysm model that conforming to its inner contour. In rabbit model, first, renal artery and aorta leading to the right kidney were ligated to block blood flow, then conventional contrast agent was injected through aorta to check the arterial patency to the left kidney. In sequential artery injection method, PGA and CaCl2 were injected through renal artery sequentially via a single catheter. Re-injection of contrast agent after removing ligated aorta showed blood flow to the right kidney but no flow in the left kidney. This result demonstrated a complete blocking of blood flow due to gel formation in vascular bed of the left kidney. Instillation of calcium alginate into aneurysm model and arterial system in vivo produced an embolization that better fills and conforms to the contour of aneurysms or blocking vascular bed completely. Therefore, PGA was effective endovascular occlusion materials and provide an efficiency of vascular angiography.

  17. Immobilization of Laccase in Alginate-Gelatin Mixed Gel and Decolorization of Synthetic Dyes

    Science.gov (United States)

    Mogharabi, Mehdi; Nassiri-Koopaei, Nasser; Bozorgi-Koushalshahi, Maryam; Nafissi-Varcheh, Nastaran; Bagherzadeh, Ghodsieh; Faramarzi, Mohammad Ali

    2012-01-01

    Alginate-gelatin mixed gel was applied to immobilized laccase for decolorization of some synthetic dyes including crystal violet. The immobilization procedure was accomplished by adding alginate to a gelatin solution containing the enzyme and the subsequent dropwise addition of the mixture into a stirred CaCl2 solution. The obtained data showed that both immobilized and free enzymes acted optimally at 50°C for removal of crystal violet, but the entrapped enzyme showed higher thermal stability compared to the free enzyme. The immobilized enzyme represented optimum decolorization at pH 8. Reusability of the entrapped laccase was also studied and the results showed that ca. 85% activity was retained after five successive cycles. The best removal condition was applied for decolorization of seven other synthetic dyes. Results showed that the maximum and minimum dye removal was related to amido black 10B and eosin, respectively. PMID:22899898

  18. Immobilization of Laccase in Alginate-Gelatin Mixed Gel and Decolorization of Synthetic Dyes

    Directory of Open Access Journals (Sweden)

    Mehdi Mogharabi

    2012-01-01

    Full Text Available Alginate-gelatin mixed gel was applied to immobilized laccase for decolorization of some synthetic dyes including crystal violet. The immobilization procedure was accomplished by adding alginate to a gelatin solution containing the enzyme and the subsequent dropwise addition of the mixture into a stirred CaCl2 solution. The obtained data showed that both immobilized and free enzymes acted optimally at 50°C for removal of crystal violet, but the entrapped enzyme showed higher thermal stability compared to the free enzyme. The immobilized enzyme represented optimum decolorization at pH 8. Reusability of the entrapped laccase was also studied and the results showed that ca. 85% activity was retained after five successive cycles. The best removal condition was applied for decolorization of seven other synthetic dyes. Results showed that the maximum and minimum dye removal was related to amido black 10B and eosin, respectively.

  19. Mechanical properties and morphology of polymer gels

    Science.gov (United States)

    Sliozberg, Yelena; Sirk, Timothy; Brennan, John; Andzelm, Jan; Mrozek, Randy; Lenhart, Joseph

    2012-02-01

    Understanding morphology and mechanical response of polymeric gels is of particular importance to design materials with required energy dissipation characteristics. We will present our latest results for polymer gels based on 1) self-assembled block copolymers and 2) chemically cross-linked polymers. The dissipative particle dynamics (DPD) was used to predict morphology in good agreement with atomic force microscopy. We have performed DPD non-equilibrium oscillatory shear calculations predicting elastic modulus of unentangled gels that correlates well with experimental rheology data. However, this methodology fails to predict mechanics of entangled polymer networks due to unphysical chain crossing brought by the soft potentials used in DPD simulations. Recently, we have introduced an improved segmental repulsion potential that removes the bond crossing allowing for reptation dynamics. The improved DPD method was used in simulations for entangled gels to explore impact of branched architecture of solvent on the mechanical response to the tensile deformation. Novel architectures of solvent resulting in a dramatic increase of the elastic modulus were identified. The topological analysis was applied to understand contributions of chemical cross-links and entanglements to the stress.

  20. Regenerative material for aneurysm embolization A 3-dimensional culture system of fibroblasts and calcium alginate gel

    Institute of Scientific and Technical Information of China (English)

    Jingdong Zhang; Kan Xu; Jinlu Yu; Jun Wang; Qi Luo

    2011-01-01

    Calcium alginate gel (CAG) has been shown to successfully model aneurysm embolization within a short period of time. However, gradually degrading CAG potentially results in aneurysm recanalization.In the present study, a regenerative embolic material was designed by seeding rat fibroblasts in a CAG. The study investigated the feasibility of constructing a 3-dimensional culture system. The fibroblasts grew well and firmly attached to the CAG. CAG was conducive for fibroblast growth, and resulted in a 3-dimensional culture system. Results show that CAG can be used theoretically as a vascular, regenerative, embolic material.

  1. Improved delivery of biocontrol Pseudomonas and their antifungal metabolites using alginate polymers.

    Science.gov (United States)

    Russo, A; Moënne-Loccoz, Y; Fedi, S; Higgins, P; Fenton, A; Dowling, D N; O'Regan, M; O'Gara, F

    1996-02-01

    Alginate polymer was evaluated as a carrier for seed inoculation with a genetically modified strain Pseudomonas fluorescens F113LacZY, which protects sugar-beet against Pythium-mediated damping-off. F113LacZY survived in alginate beads at 5 log10 CFU/bead or higher counts for 8 weeks of storage, regardless of the conditions of incubation. In plant inoculation experiments, colonisation of the growing area of the root by F113LacZY, derived from alginate beads placed in the soil next to the seed or from an alginate coating around the seeds, was improved compared with application of just free cells of the strain. F113LacZY trapped in alginate beads was an effective producer of antifungal phloroglucinols as indicated by direct HPLC quantification of phloroglucinols and in vitro inhibition of both the indicator bacterium Bacillus subtilis A1 and the pathogenic fungus Pythium ultimum. Alginate polymer represents a promising carrier for the delivery of biocontrol inoculants for root colonisation and production of antifungal metabolites. PMID:8867631

  2. Polymer gel dosimetry system for radiation therapy

    International Nuclear Information System (INIS)

    Purpose/Objective: Recently developed treatment modalities such as stereotactic and conformal radiation therapy produce complex dose distributions which are difficult or impractical to measure with conventional dosimetry instrumentation. Three-dimensional treatment planning systems which purport to calculate these complex dose distributions should be compared to experimental results before being routinely applied to clinical problems. There is a need for a new class of tissue-equivalent dosimeters capable of providing accurate, high resolution, time-integrated and three dimensional dose distributions. The recently developed BANG polymer gel dosimetry system (MGS Research, Inc., Guilford, CT) is ideally suited for the task described above. Physico-chemical principles of the polymer gel dosimetry are presented, together with examples of its application to radiation therapy. Data analysis and display program, written for Macintosh computer, is demonstrated. Materials and Methods: Radiation-induced polymerization of acrylic monomers, which are dispersed in tissue-equivalent gelatin, has been shown to be dependent on the dose, but independent of the dose rate or photon energy. Therefore, the spatial distribution of polymer in the gel is precisely representative of the dose distribution. As the polymeric microparticles reduce the water proton NMR relaxation times in the gel, the dose distribution can be measured with high resolution and accuracy using magnetic resonance imaging. Also, as these microparticles cannot diffuse through the gelatin matrix, their distribution is permanent. An improved formulation of the BANG dosimeter consists of 3% w/v acrylic acid, 3% N,N'-methylene-bis-acrylamide, 1% sodium hydroxide, 5% gelatin, and 88% water. MR images are transferred via a local network to a Macintosh computer, and R2 maps constructed on the basis of multiple TE images, using a non-linear least squares fit based on the Levenberg-Marquardt algorithm. A dose-to-R2

  3. Optical-CT scanning of polymer gels

    International Nuclear Information System (INIS)

    The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data

  4. Carbon Redox-Polymer-Gel Hybrid Supercapacitors

    Science.gov (United States)

    Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P. M.

    2016-02-01

    Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances.

  5. SURFACE DYNAMIC FRICTION OF POLYMER GELS

    Institute of Scientific and Technical Information of China (English)

    J.P.Gong; G.Kagata; Y.Iwasaki; Y.Osada

    2000-01-01

    The sliding friction of various kinds of hydrogels has been studied and it was found that the frictional behaviors of the hydrogels do not conform to Amonton's law F =μW which well describes the friction of solids. The frictional force and its dependence on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition. The gel friction is explained in terms of interfacial interaction, either attractive or repulsive, between the polymer chain and the solid surface. According to this model, the friction is ascribed to the viscous flow of solvent at the interface in the repulsive case. In the attractive case, the force to detach the adsorbing chain from the substrate appears as friction. The surface adhesion between glass particles and gels measured by AFM showed a good correlation with the friction, which supported the repulsion-adsorption model proposed by the authors.

  6. Polymer and Polymer Gel of Liquid Crystalline Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

    2004-01-01

    It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

  7. Calcium alginate gels as stem cell matrix-making paracrine stem cell activity available for enhanced healing after surgery.

    Directory of Open Access Journals (Sweden)

    Andreas Schmitt

    Full Text Available Regeneration after surgery can be improved by the administration of anabolic growth factors. However, to locally maintain these factors at the site of regeneration is problematic. The aim of this study was to develop a matrix system containing human mesenchymal stem cells (MSCs which can be applied to the surgical site and allows the secretion of endogenous healing factors from the cells. Calcium alginate gels were prepared by a combination of internal and external gelation. The gelling behaviour, mechanical stability, surface adhesive properties and injectability of the gels were investigated. The permeability of the gels for growth factors was analysed using bovine serum albumin and lysozyme as model proteins. Human MSCs were isolated, cultivated and seeded into the alginate gels. Cell viability was determined by AlamarBlue assay and fluorescence microscopy. The release of human VEGF and bFGF from the cells was determined using an enzyme-linked immunoassay. Gels with sufficient mechanical properties were prepared which remained injectable through a syringe and solidified in a sufficient time frame after application. Surface adhesion was improved by the addition of polyethylene glycol 300,000 and hyaluronic acid. Humans MSCs remained viable for the duration of 6 weeks within the gels. Human VEGF and bFGF was found in quantifiable concentrations in cell culture supernatants of gels loaded with MSCs and incubated for a period of 6 weeks. This work shows that calcium alginate gels can function as immobilization matrices for human MSCs.

  8. Determination of diffusion coefficients and diffusion characteristics for chlorferon and diethylthiophosphate in Ca-alginate gel beads.

    Science.gov (United States)

    Ha, Jiyeon; Engler, Cady R; Lee, Seung Jae

    2008-07-01

    Diffusion characteristics of chlorferon and diethylthiophosphate (DETP) in Ca-alginate gel beads were studied to assist in designing and operating bioreactor systems. Diffusion coefficients for chlorferon and DETP in Ca-alginate gel beads determined at conditions suitable for biodegradation studies were 2.70 x 10(-11) m(2)/s and 4.28 x 10(-11) m(2)/s, respectively. Diffusivities of chlorferon and DETP were influenced by several factors, including viscosity of the bulk solution, agitation speed, and the concentrations of diffusing substrate and immobilized cells. Diffusion coefficients increased with increasing agitation speed, probably due to poor mixing at low speed and some attrition of beads at high speeds. Diffusion coefficients also increased with decreasing substrate concentration. Increased cell concentration in the gel beads caused lower diffusivity. Theoretical models to predict diffusivities as a function of cell weight fraction overestimated the effective diffusivities for both chlorferon and DETP, but linear relations between effective diffusivity and cell weight fraction were derived from experimental data. Calcium-alginate gel beads with radii of 1.65-1.70 mm used in this study were not subject to diffusional limitations: external mass transfer resistances were negligible based on Biot number calculations and effectiveness factors indicated that internal mass transfer resistance was negligible. Therefore, the degradation rates of chlorferon and DETP inside Ca-alginate gel beads were reaction-limited. PMID:18080347

  9. Soluble polymers in sol-gel silica

    Science.gov (United States)

    Beaudry, Christopher Laurent

    In the last few years, the inherent versatility of sol-gel processing has led to a significant research effort on inorganic/organic materials. One method of incorporating an organic phase into sol-gel silica is dissolving an organic polymer in a tetraethylorthosilicate (TEOS) solution, followed by in situ polymerization of silica in the presence of organic polymer. The first part of the study involved the development of a two-step (acid-base) synthesis procedure to allow systematic control of acidity in TEOS solutions. With this procedure, it was possible to increase the pH of the TEOS solution while correlating the acidity and properties. The properties were the gelation time, syneresis rate, drying behavior, and xerogel pore structure, as determined by nitrogen sorption. Furthermore, controlling the acidity was shown to control the silica xerogel pore structure. In the second part of the study, the two-step procedure was used to synthesize silica/poly(ethylene glycol) (PEG), and silica/poly(vinyl acetate) (PVAc) composite materials. The content of organic polymer and the molecular weight were varied. The gelation time, the syneresis rate, the drying behavior, and the pore structure were determined for compositions with 10% PEG (M.W. 2,000), 5, 10, and 15% PEG (M.W. 3,400), and 10 and 25% PVAc (M.W. 83,000). Other compositions and molecular weights of PEG lead to sedimentation. In the PEG compositions, the tendency to phase separate was correlated with the effects of the processing variables on the segregation strength and polymerization rate. The PVAc compositions did not show any visible phase separation during processing, giving the composite xerogels an appearance similar to pure silica. The property differences between gels with PEG and gels with PVAc show the relative strength of the interactions with silica. Both polymers exhibit hydrogen bonding between the phases. In the case of PEG, hydrogen bonding between the ether oxygens of the polymer and silanol

  10. Preparation and Characterization of Alginate-Hyaluronic Acid-chitosan based Composite Gel Beads

    Institute of Scientific and Technical Information of China (English)

    HU Yan; ZHENG Mengzhu; DONG Xiaoying; ZHAO Dan; CHENG Han; XIAO Xincai

    2015-01-01

    The aim of this study was to fabricate composite gel beads based on natural polysaccharides. Hyaluronic acid (HA) and Chitosan (CS) were successfully admixed with Ca2+/alginate (SA) gel system to produce SA/HA/CS gel beads by dual crosslinking:the ionic gelation and the polyelectrolyte complexation. The preparation procedure was that the weight ratio of SA (2%, m/v) to HA (2%, m/v) was kept at 2:1, then the mixture was dripped into the Ca2+solution for ion-crosslinking, and finally polyelectrolyte crosslinked with 2%low molecular weight CS (LMW-CS) for 1.5 hours. The optimal formulation was achieved by adjusting the concentration and the weight ratio of SA, HA and LMW-CS. Due to the incorporation of HA and LMW-CS, the swelling ratio of the beads at pH 7.4 was increased up to 120, and the time for the maximum swelling degree was prolonged to 7.5 h. The swelling behavior was obviously improved compared to the pure SA/Ca2+system. The preliminary results clearly suggest that the SA/HA/CS gel beads may be a potential candidate for biomedical delivery vehicles.

  11. Small-angle X-ray scattering and rheological characterization of alginate gels. 2. Time-resolved studies on ionotropic gels

    Science.gov (United States)

    Yuguchi, Y.; Urakawa, H.; Kajiwara, K.; Draget, K. I.; Stokke, B. T.

    2000-10-01

    Gelation was observed by time-resolved small-angle X-ray scattering and rheology on 10 mg/ml Ca-alginate gels prepared by in situ release of Ca 2+ from CaEGTA or CaCO 3 with total Ca 2+ concentration in the range 10-20 mM. This was carried out for alginates having a fraction of α- L-GulA (G) of FG=0.39 and 0.68, respectively, obtained by the selection of alginates isolated from two different brown algae, Ascophyllum nodosum and Laminaria hyperborea stipe. Correlation between the rheological data and SAXS data shows that a large fraction of the lateral association precedes the formation of a continuous network through the sample cell. Following the initial association of chain segments in junction zones, the analysis using two-component broken rod model indicates the formation of larger bundles, and that the relative weight of these bundles increases with increasing time. The molecular model for the bundles is proposed by associating 2-16 units (G-blocks) composed of 14 (1→4) linked residues of α- L-GulA in parallel according to the available crystallographic data. The storage modulus increases as the bundles composed of associated alginate chains grow during the gel formation. The gel elasticity is mainly sustained by single chains in the alginate sample with a low fraction of α- L-GulA. The alginates with a high fraction of α- L-GulA associate into thicker bundles which join to form a network. Here the gel elasticity seems to be due to the flexible joints between bundles, since the fraction of single chains is extremely low.

  12. Effects of Composition of Iron-Cross-Linked Alginate Hydrogels for Cultivation of Human Dermal Fibroblasts

    Directory of Open Access Journals (Sweden)

    Ikuko Machida-Sano

    2012-01-01

    Full Text Available We investigated the suitability of ferric-ion-cross-linked alginates (Fe-alginate with various proportions of L-guluronic acid (G and D-mannuronic acid (M residues as a culture substrate for human dermal fibroblasts. High-G and high-M Fe-alginate gels showed comparable efficacy in promoting initial cell adhesion and similar protein adsorption capacities, but superior cell proliferation was observed on high-G than on high-M Fe-alginate as culture time progressed. During immersion in culture medium, high-G Fe-alginate showed little change in gel properties in terms of swelling and polymer content, but the properties of high-M Fe-alginate gel were altered due to loss of ion cross-linking. However, the degree of cell proliferation on high-M Fe-alginate gel was improved after it had been stabilized by immersion in culture medium until no further changes occurred. These results suggest that the mode of cross-linkage between ferric ions and alginate differs depending on alginate composition and that the major factor giving rise to differences in cell growth on the two types of Fe-alginate films is gel stability during culture, rather than swelling of the original gel, polymer content, or protein adsorption ability. Our findings may be useful for extending the application of Fe-alginate to diverse biomedical fields.

  13. Antioxidant effect of green tea on polymer gel dosimeter

    International Nuclear Information System (INIS)

    Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer

  14. Antioxidant effect of green tea on polymer gel dosimeter

    Science.gov (United States)

    Samuel, E. J. J.; Sathiyaraj, P.; Deena, T.; Kumar, D. S.

    2015-01-01

    Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.

  15. Gelation and biocompatibility of injectable alginate-calcium phosphate gels for bone regeneration.

    Science.gov (United States)

    Cardoso, D Alves; van den Beucken, J J J P; Both, L L H; Bender, J; Jansen, J A; Leeuwenburgh, S C G

    2014-03-01

    An emerging approach toward development of injectable, self-setting, and fully biodegradable bone substitutes involves the combination of injectable hydrogel matrices with a dispersed phase consisting of nanosized calcium phosphate particles. Here, novel injectable composites for bone regeneration have been developed based on the combination of ultrapure alginate as the matrix phase, crystalline CaP [monetite and poorly crystalline hydroxyapatite (HA)] powders as both a dispersed mineral phase and a source of calcium for cross-linking alginate, glucono-delta-lactone (GDL) as acidifier and glycerol as both plasticizer and temporary sequestrant. The composites were maximized with respect to CaP content to obtain the highest amount of osteoconductive filler. The viscoelastic and physicochemical properties of the precursor compounds and composites were analyzed using rheometry, elemental analysis (for calcium release and uptake), acidity [by measuring pH in simulated body fluid (SBF)], general biocompatibility (subcutaneous implantation in rabbits), and osteocompatibility (implantation in femoral condyle bone defect of rabbits). The gelation of the resulting composites could be controlled from seconds to tens of minutes by varying the solubility of the CaP phase (HA vs. monetite) or amount of GDL. All composites mineralized extensively in SBF for up to 11 days. In vivo, the composites also disintegrated upon implantation in subcutaneous or bone tissue, leaving behind less degradable but osteoconductive CaP particles. Although the composites need to be optimized with respect to the available amount of calcium for cross-linking of alginate, the beneficial bone response as observed in the in vivo studies render these gels promising for minimally invasive applications as bone-filling material.

  16. CURRENT COLLOIDAL DISPERSION GELS ARE NOT SUPERIOR TO POLYMER FLOODING

    Institute of Scientific and Technical Information of China (English)

    Seright Randy; Han Peihui; Wang Dongmei

    2006-01-01

    The suggestion that the colloidal-dispersion-gel (CDG) process is superior to normal polymer flooding is misleading and generally incorrect. Colloidal dispersion gels, in their present state of technological development, should not be advocated as an improvement to, or substitute for, polymer flooding. Gels made from aluminum-citrate crosslinked polyacrylamides can act as conventional gels and provide effective conformance improvement in treating some types of excess water production problems if sound scientific and engineering principles are respected.

  17. Freeze-thaw induced gelation of alginates.

    Science.gov (United States)

    Zhao, Ying; Shen, Wei; Chen, Zhigang; Wu, Tao

    2016-09-01

    Adding divalent ions or lowering pH below the pKa values of alginate monomers are common ways in preparing alginate gels. Herein a new way of preparing alginate gels using freeze-thaw technique is described. Solvent crystallization during freezing drove the polymers to associate into certain structures that became the junction zones of hydrogels after thawing. It enabled the preparation of alginate gels at pH 4.0 and 3.5, two pH at which the gel could not be formed previously. At pH 3.0 where alginate gel could be formed initially, applying freeze-thaw treatment increased the gel storage modulus almost 100 times. The formation of hydrogels and the resulting gel properties, such as dynamic moduli and gel syneresis were influenced by the pH values, number of freeze-thaw cycles, alginate concentrations, and ionic strengths. The obtained hydrogels were soft and demonstrated a melting behavior upon storage, which may find novel applications in the biomedical industry.

  18. Freeze-thaw induced gelation of alginates.

    Science.gov (United States)

    Zhao, Ying; Shen, Wei; Chen, Zhigang; Wu, Tao

    2016-09-01

    Adding divalent ions or lowering pH below the pKa values of alginate monomers are common ways in preparing alginate gels. Herein a new way of preparing alginate gels using freeze-thaw technique is described. Solvent crystallization during freezing drove the polymers to associate into certain structures that became the junction zones of hydrogels after thawing. It enabled the preparation of alginate gels at pH 4.0 and 3.5, two pH at which the gel could not be formed previously. At pH 3.0 where alginate gel could be formed initially, applying freeze-thaw treatment increased the gel storage modulus almost 100 times. The formation of hydrogels and the resulting gel properties, such as dynamic moduli and gel syneresis were influenced by the pH values, number of freeze-thaw cycles, alginate concentrations, and ionic strengths. The obtained hydrogels were soft and demonstrated a melting behavior upon storage, which may find novel applications in the biomedical industry. PMID:27185114

  19. Investigating potential physicochemical errors in polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Sedaghat, Mahbod; Lepage, Martin [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); Bujold, Rachel, E-mail: martin.lepage@usherbrooke.ca [Service de radio-oncologie, Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC (Canada)

    2011-09-21

    Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

  20. How to scan polymer gels with MRI?

    Science.gov (United States)

    De Deene, Y.

    2013-06-01

    The absorbed radiation dose fixated in a polymer gel dosimeter can be read out by several methods such as magnetic resonance imaging (MRI), optical CT, X-ray CT and ultrasound with MRI being the first method that was explored. Although MRI was considered as an elegant scanning technique, readily available in most hospitals, it was later found that using a non-optimized imaging protocol may result in unacceptable deviations in the obtained dose distribution. Although most medical physicists have an understanding of the basic principles of magnetic resonance imaging (MRI), the optimization of quantitative imaging sequences and protocols is often perceived as the work of MRI experts. In this paper, we aim at providing the reader with some easy guidelines in how to obtain reliable quantitative MRI maps.

  1. Drying and shrinkage of polymer gels

    Directory of Open Access Journals (Sweden)

    S. S. Waje

    2005-06-01

    Full Text Available The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 ºC in presence of Photo-initiator (IrgacureR and Cross-linker (NN'-methylene bisacrylamide; MBAM. In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM, concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10-10-5.93 ´ 10-10 m²/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.

  2. Stabilization of polymer gels against divalent ion-induced syneresis

    Energy Technology Data Exchange (ETDEWEB)

    Albonico, Paola; Lockhart, Thomas P. [Eniricerche SpA, San Donato, Milan (Italy)

    1997-07-15

    Polymer solutions and polymer gels are unstable to extended ageing in divalent cation-rich brines at elevated temperature. This paper shows that low-molecular-weight compounds that complex strongly with Ca{sup 2+} and Mg{sup 2+} are capable of neutralizing their destabilizing influence on polymer solubility and of inhibiting the syneresis of crosslinked acrylamide polymer gels in hard brines. The solubility of the inhibitor-divalent ion complexes formed in hard brine at elevated temperature have also been examined. The results obtained offer the possibility to extend significantly the upper temperature limit for the use of polyacrylamides and acrylamide copolymers in brines in both polymer flooding and polymer gel treatments

  3. Fabrication and evaluation of biomimetic scaffolds by using collagen-alginate fibrillar gels for potential tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Sang Lin; Luo Dongmei; Xu Songmei; Wang Xiaoliang; Li Xudong, E-mail: xli20004@yahoo.com

    2011-03-12

    Pore architecture and its stable functionality under cell culturing of three dimensional (3D) scaffolds are of great importance for tissue engineering purposes. In this study, alginate was incorporated with collagen to fabricate collagen-alginate composite scaffolds with different collagen/alginate ratios by lyophilizing the respective composite gels formed via collagen fibrillogenesis in vitro and then chemically crosslinking. The effects of alginate amount and crosslinking treatment on pore architecture, swelling behavior, enzymatic degradation and tensile property of composite scaffolds were systematically investigated. The relevant results indicated that the present strategy was simple but efficient to fabricate highly interconnected strong biomimetic 3D scaffolds with nanofibrous surface. NIH3T3 cells were used as a model cell to evaluate the cytocompatibility, attachment to the nanofibrous surface and porous architectural stability in terms of cell proliferation and infiltration within the crosslinked scaffolds. Compared with the mechanically weakest crosslinked collagen sponges, the cell-cultured composite scaffolds presented a good porous architecture, thus permitting cell proliferation on the top surface as well as infiltration into the inner part of 3D composite scaffolds. These composite scaffolds with pore size ranging from 150 to 300 {mu}m, over 90% porosity, tuned biodegradability and water-uptake capability are promising for tissue engineering applications.

  4. Fabrication and evaluation of biomimetic scaffolds by using collagen-alginate fibrillar gels for potential tissue engineering applications

    International Nuclear Information System (INIS)

    Pore architecture and its stable functionality under cell culturing of three dimensional (3D) scaffolds are of great importance for tissue engineering purposes. In this study, alginate was incorporated with collagen to fabricate collagen-alginate composite scaffolds with different collagen/alginate ratios by lyophilizing the respective composite gels formed via collagen fibrillogenesis in vitro and then chemically crosslinking. The effects of alginate amount and crosslinking treatment on pore architecture, swelling behavior, enzymatic degradation and tensile property of composite scaffolds were systematically investigated. The relevant results indicated that the present strategy was simple but efficient to fabricate highly interconnected strong biomimetic 3D scaffolds with nanofibrous surface. NIH3T3 cells were used as a model cell to evaluate the cytocompatibility, attachment to the nanofibrous surface and porous architectural stability in terms of cell proliferation and infiltration within the crosslinked scaffolds. Compared with the mechanically weakest crosslinked collagen sponges, the cell-cultured composite scaffolds presented a good porous architecture, thus permitting cell proliferation on the top surface as well as infiltration into the inner part of 3D composite scaffolds. These composite scaffolds with pore size ranging from 150 to 300 μm, over 90% porosity, tuned biodegradability and water-uptake capability are promising for tissue engineering applications.

  5. Insulin release from islets of Langerhans entrapped in a poly(N-isopropylacrylamide-co-acrylic acid) polymer gel.

    Science.gov (United States)

    Vernon, B; Kim, S W; Bae, Y H

    1999-01-01

    A copolymer of N-isopropylacrylamide (98 mol% in feed) and acrylic acid, poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)), was prepared by free radical polymerization for development of a thermally reversible polymer to entrap islets of Langerhans for a refillable biohybrid artificial pancreas. A 5 wt% solution of the polymer in Hanks' balanced salt solution forms a gel at 37 degrees C that exhibits no syneresis. Diffusion of fluorescein isothiocyanate (FITC) dextrans having molecular weights of 4400 and 70000 were used to evaluate mass transport in the gel at 37 degrees C. Insulin secretion from islets in the polymer gel was also investigated in both static and dynamic systems. The polymer gel exhibited excellent diffusion of FITC dextran 4400 and FITC dextran 70000 with diffusion ratios, D/D0 (ratio of diffusion in the gel to diffusion in water), of 0.20+/-0.04 and 0.35+/-0.17, respectively. Human islets entrapped in the polymer gel showed prolonged insulin secretion in response to basal (5.5 mM) glucose concentration compared to free human islets. Rat islets showed prolonged insulin secretion in response to high (16.5 mM) glucose concentrations compared to free rat islets. Rat islets in the polymer gel maintained insulin secretion in response to the higher glucose concentration for over 26 days. Rat islets entrapped by the polymer also released higher quantities of insulin more rapidly in response to changes in concentrations of glucose and other stimulants than rat islets entrapped in an alginate control. These results suggest that this material would provide adequate diffusion for rapid insulin release in an application as a synthetic extracellular matrix for a biohybrid artificial pancreas.

  6. Optimisation of decolourisation and degradation of Reactive Black 5 dye under electro-Fenton process using Fe alginate gel beads.

    Science.gov (United States)

    Iglesias, O; Fernández de Dios, M A; Rosales, E; Pazos, M; Sanromán, M A

    2013-04-01

    The aim of this work was to improve the ability of the electro-Fenton process using Fe alginate gel beads for the remediation of wastewater contaminated with synthetic dyes and using a model diazo dye such as Reactive Black 5 (RB5). Batch experiments were conducted to study the effects of main parameters, such as voltage, pH and iron concentration. Dye decolourisation, reduction of chemical oxygen demand (COD) and energy consumption were studied. Central composite face-centred experimental design matrix and response surface methodology were applied to design the experiments and to evaluate the interactive effects of the three studied parameters. A total of 20 experimental runs were set, and the kinetic data were analysed using first-order and second-order models. In all cases, the experimental data were fitted to the empirical second-order model with a suitable degree for the maximum decolourisation of RB5, COD reduction and energy consumption by electro-Fenton-Fe alginate gel beads treatment. Working with the obtained empirical model, the optimisation of the process was carried out. The second-order polynomial regression model suggests that the optimum conditions for attaining maximum decolourisation, COD reduction and energy consumption are voltage, 5.69 V; pH 2.24 and iron concentration, 2.68 mM. Moreover, the fixation of iron on alginate beads suggests that the degradation process can be developed under this electro-Fenton process in repeated batches and in a continuous mode.

  7. Diffusion loading and drug delivery characteristics of alginate gel microparticles produced by a novel impinging aerosols method.

    Science.gov (United States)

    Hariyadi, Dewi M; Lin, Sharon Chien-Yu; Wang, Yiwei; Bostrom, Thor; Turner, Mark S; Bhandari, Bhesh; Coombes, Allan G A

    2010-12-01

    Microencapsulation of a hydrophilic active (gentamicin sulphate (GS)) and a hydrophobic non-steroidal anti-inflammatory drug (ibuprofen) in alginate gel microparticles was accomplished by molecular diffusion of the drug species into microparticles produced by impinging aerosols of alginate solution and CaCl(2) cross-linking solution. A mean particle size in the range of 30-50 µm was measured using laser light scattering and high drug loadings of around 35 and 29% weight/dry microparticle weight were obtained for GS and ibuprofen respectively. GS release was similar in simulated intestinal fluid (phosphate buffer saline (PBS), pH 7.4, 37°C) and simulated gastric fluid (SGF) (HCl, pH 1.2, 37°C) but was accelerated in PBS following incubation of microparticles in HCl. Ibuprofen release was restricted in SGF but occurred freely on transfer of microparticles into PBS with almost 100% efficiency. GS released in PBS over 7 h, following incubation of microparticles in HCl for 2 h was found to retain at least 80% activity against Staphylococcus epidermidis while Ibuprofen retained around 50% activity against Candida albicans. The impinging aerosols technique shows potential for producing alginate gel microparticles of utility for protection and controlled delivery of a range of therapeutic molecules.

  8. Encapsulated human hepatocellular carcinoma cells by alginate gel beads as an in vitro metastasis model

    International Nuclear Information System (INIS)

    Hepatocellular carcinoma (HCC) is the most common primary liver cancer and often forms metastases, which are the most important prognostic factors. For further elucidation of the mechanism underlying the progression and metastasis of HCC, a culture system mimicking the in vivo tumor microenvironment is needed. In this study, we investigated the metastatic ability of HCC cells cultured within alginate gel (ALG) beads. In the culture system, HCC cells formed spheroids by proliferation and maintained in nuclear abnormalities. The gene and protein expression of metastasis-related molecules was increased in ALG beads, compared with the traditional adhesion culture. Furthermore, several gene expression levels in ALG bead culture system were even closer to liver cancer tissues. More importantly, in vitro invasion assay showed that the invasion cells derived from ALG beads was 7.8-fold higher than adhesion cells. Our results indicated that the in vitro three-dimensional (3D) model based on ALG beads increased metastatic ability compared with adhesion culture, even partly mimicked the in vivo tumor tissues. Moreover, due to the controllable preparation conditions, steady characteristics and production at large-scale, the 3D ALG bead model would become an important tool used in the high-throughput screening of anti-metastasis drugs and the metastatic mechanism research. -- Highlights: •We established a 3D metastasis model mimicking the metastatic ability in vivo. •The invasion ability of cells derived from our model was increased significantly. •The model is easy to reproduce, convenient to handle, and amenable for large-scale

  9. Removal of some divalent cations from water by membrane-filtration assisted with alginate.

    Science.gov (United States)

    Fatin-Rouge, Nicolas; Dupont, Alexandra; Vidonne, Alain; Dejeu, Jérome; Fievet, Patrick; Foissy, Alain

    2006-03-01

    The removal of divalent metal ions from hard waters or galvanic wastewater by polymer-assisted membrane filtration using alginate was investigated. The ability of this natural polymer to form aggregates and gels in presence of metal ions was studied, in order to carry out metal removal by ultra or micro-filtration. Alginate titrations have shown the presence of amine groups in addition to carboxylates onto the polymer backbone. The binding properties of alginate with divalent cations have been studied, showing an increasing affinity for Ca2+ over Mg2+ as polymer concentration increases, and the relative affinity Pb2+ > or = Cu2+ > Zn2+ > Ni2+. The softening of hard natural waters was achieved successfully and easily, but needs an optimal alginate concentration approximately 4 x 10(-2) M. The alginate powder can be directly added to hard waters. Except for Ni2+, metal-removal was efficient. Polymer regeneration has shown that Cu2+-complexes are labiles.

  10. A comparative study of new type polymer gel dosimeters

    International Nuclear Information System (INIS)

    In this study we have investigated and evaluated some dosimetric properties of polymer gel dosimeter encountered when using gels in clinical radiation therapy environment. Four different compositions of polymer gel dosimeter were manufactured. Two compositions (A and D) represent widely recognized gels prepared following literature instructions. In case of MAGIC type dosimeter (D), gelatin weight fraction was decreased to 5%. During our previous research, we have experienced some substantial changes in behavior when lowering amount of sodium hydroxide and when potassium aluminum sulfate was added. Therefore another two gels were prepared (B and C). Gel dosimeters were evaluated using transversal relaxation rate R2. Details of the used acquisition sequence may be found in Spevacek V. et.al. (2001), only eight echo times were used for R2 calculation in this case. The following properties have been investigated for the four gel compositions: dose response; temperature dependence of dose response; short and long term stability; behavior of gels in a region of steep dose gradient; and uniformity of homogeneously irradiated region. (authors)

  11. Morphology of Polyvinylidene Fluoride Based Gel Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    田立颖; 黄小彬; 唐小真

    2004-01-01

    Two series of polyvinylidene fluoride (PVDF) based gel polymer electrolytes, with different LiClO4 or propylene carbonate (PC) content, were prepared and analyzed by infrared spectrometer, differential scanning calorimetry, scanning electron microscope and complex impedance spectrometer. The results show that there are great interactions between PVDF, PC and lithium cations. Both LiClO4 and PC content lead to evident change of the morphology of the gel polymer electrolytes. The content of LiClO4 and PC also influences the ionic conductivity of the samples,and an ionic conductivity of above 10-3S·cm-1 can be reached at room temperature.

  12. PMMA-based Gel Polymer Electrolytes with Crosslinking Network

    Institute of Scientific and Technical Information of China (English)

    H.P. Zhang; Y. P. Wu; H. Q. Wu; M. Sun

    2005-01-01

    @@ 1Introduction The lithium-ion battery has a good rate capability and low-temperature performance, but its safety is relatively low due to the possibility of leakage of liquid electrolyte. The use of a solid or gel type electrolyte can lower the probability of leakage liquid electrolyte, and the electrochemical performance of gel electrolyte doesn't decrease so markedly as the solid electrolyte. Now, new types of advanced lithium-ion battery with gel polymer electrolytes are under developing which can be used in the future.

  13. Nonlinear dynamics of self-oscillating polymer gels

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Self-oscillating polymer gels driven by Belousov-Zhabotinsky (BZ) chemical reaction are a new class of functional gels that have a wide range of potential applications (e.g., autonomously functioning membranes, actuate artificial muscles). However, the precise control of these gels has been an issue due to limited investigations of the influences of key system parameters on the characteristics of BZ gels. To address this deficiency, we studied the self-oscillating behavior of BZ gels using the nonline-ar dynamics theory and an Oregonator-like model, with focus placed upon the influences of various system parameters. The analysis of the oscillation phase indicated that the dynamic response of BZ gels represents the classical limit cycle oscillation. We then investigated the characteristics of the limit cycle oscillation and quantified the influences of key parameters (i.e., ini-tial reactant concentration, oxidation and reduction rate of catalyst, and response coefficient) on the self-oscillating behavior of BZ gels. The results demonstrated that sustained limit cycle oscillation of BZ gels can be achieved only when these key pa-rameters meet certain requirements, and that the pattern, period and amplitude of the oscillation are significantly influenced by these parameters. The results obtained in this study could enable the controlled self-oscillation of BZ gels system. This has several potential applications such as controlled drug delivery, miniature peristaltic pumps and microactuators.

  14. Carbon beam dosimetry using VIP polymer gel and MRI

    DEFF Research Database (Denmark)

    Kantemiris, I; Petrokokkinos, L; Angelopoulos, A;

    2009-01-01

    VIP polymer gel dosimeter was used for Carbon ion beam dosimetry using a 150 MeV/n beam with 10 Gy plateau dose and a SOBP irradiation scheme with 5 Gy Bragg peak dose. The results show a decrease by 8 mm in the expected from Monte Carlo simulation range in water, suggesting that the dosimeter...

  15. Rheology and Relaxation Timescales of ABA Triblock Polymer Gels

    Science.gov (United States)

    Peters, Andrew; Lodge, Timothy

    When dissolved in a midblock selective solvent, ABA polymers form gels composed of aggregated end block micelles bridged by the midblocks. While much effort has been devoted to the study of the structure of these systems, the dynamics of these systems has received less attention. We examine the underlying mechanism of shear relaxation of ABA triblock polymer gels, especially as a function of chain length, composition, and concentration. Recent work using time-resolved small-angle neutron scattering of polystyrene (PS)-block-poly(ethylene-alt-propylene) (PEP) in squalane has elucidated many aspects of the dynamics of diblock chain exchange. By using rheology to study bulk relaxation phenomena of the triblock equivalent, PS-PEP-PS, we apply the knowledge gained from the chain exchange studies to bridge the gap between the molecular and macroscopic relaxation phenomena in PS-PEP-PS triblock gels.

  16. NMR study of starch based polymer gel electrolytes: Humidity effects

    International Nuclear Information System (INIS)

    In this work, nuclear magnetic resonance spectroscopy (NMR) was used to study the effect of water absorption in polymer gel electrolytes formed by amylopectin rich starch, plasticized with glycerol and containing lithium perchlorate. The position of the 7Li spin-lattice relaxation rate maximum is shifted progressively towards lower temperatures with increasing hydration, reflecting an increase of the lithium mobility. The mechanism responsible for the spin-lattice relaxation of the 7Li nuclei in the gel electrolytes are the fluctuations of the quadrupolar interaction due to the lithium motions. The 7Li relaxation results of the gel electrolyte hydrated with 2.2 water per complex unit suggest that the lithium ions are almost decoupled from the polymer chain and coordinate, hence preferring the water molecules

  17. Enzymatic Hydrolysis of Alginate to Produce Oligosaccharides by a New Purified Endo-Type Alginate Lyase

    Science.gov (United States)

    Zhu, Benwei; Chen, Meijuan; Yin, Heng; Du, Yuguang; Ning, Limin

    2016-01-01

    Enzymatic hydrolysis of sodium alginate to produce alginate oligosaccharides has drawn increasing attention due to its advantages of containing a wild reaction condition, excellent gel properties and specific products easy for purification. However, the efficient commercial enzyme tools are rarely available. A new alginate lyase with high activity (24,038 U/mg) has been purified from a newly isolated marine strain, Cellulophaga sp. NJ-1. The enzyme was most active at 50 °C and pH 8.0 and maintained stability at a broad pH range (6.0–10.0) and temperature below 40 °C. It had broad substrate specificity toward sodium alginate, heteropolymeric MG blocks (polyMG), homopolymeric M blocks (polyM) and homopolymeric G blocks (polyG), and possessed higher affinity toward polyG (15.63 mM) as well as polyMG (23.90 mM) than polyM (53.61 mM) and sodium alginate (27.21 mM). The TLC and MS spectroscopy analysis of degradation products suggested that it completely hydrolyzed sodium alginate into oligosaccharides of low degrees of polymerization (DPs). The excellent properties would make it a promising tool for full use of sodium alginate to produce oligosaccharides. PMID:27275826

  18. A simple, quantitative method using alginate gel to determine rat colonic tumor volume in vivo.

    Science.gov (United States)

    Irving, Amy A; Young, Lindsay B; Pleiman, Jennifer K; Konrath, Michael J; Marzella, Blake; Nonte, Michael; Cacciatore, Justin; Ford, Madeline R; Clipson, Linda; Amos-Landgraf, James M; Dove, William F

    2014-04-01

    Many studies of the response of colonic tumors to therapeutics use tumor multiplicity as the endpoint to determine the effectiveness of the agent. These studies can be greatly enhanced by accurate measurements of tumor volume. Here we present a quantitative method to easily and accurately determine colonic tumor volume. This approach uses a biocompatible alginate to create a negative mold of a tumor-bearing colon; this mold is then used to make positive casts of dental stone that replicate the shape of each original tumor. The weight of the dental stone cast correlates highly with the weight of the dissected tumors. After refinement of the technique, overall error in tumor volume was 16.9% ± 7.9% and includes error from both the alginate and dental stone procedures. Because this technique is limited to molding of tumors in the colon, we utilized the Apc(Pirc/+) rat, which has a propensity for developing colonic tumors that reflect the location of the majority of human intestinal tumors. We have successfully used the described method to determine tumor volumes ranging from 4 to 196 mm³. Alginate molding combined with dental stone casting is a facile method for determining tumor volume in vivo without costly equipment or knowledge of analytic software. This broadly accessible method creates the opportunity to objectively study colonic tumors over time in living animals in conjunction with other experiments and without transferring animals from the facility where they are maintained.

  19. Sustained Delivery of Bioactive GDNF from Collagen and Alginate-Based Cell-Encapsulating Gel Promoted Photoreceptor Survival in an Inherited Retinal Degeneration Model.

    Directory of Open Access Journals (Sweden)

    Francisca S Y Wong

    Full Text Available Encapsulated-cell therapy (ECT is an attractive approach for continuously delivering freshly synthesized therapeutics to treat sight-threatening posterior eye diseases, circumventing repeated invasive intravitreal injections and improving local drug availability clinically. Composite collagen-alginate (CAC scaffold contains an interpenetrating network that integrates the physical and biological merits of its constituents, including biocompatibility, mild gelling properties and availability. However, CAC ECT properties and performance in the eye are not well-understood. Previously, we reported a cultured 3D CAC system that supported the growth of GDNF-secreting HEK293 cells with sustainable GDNF delivery. Here, the system was further developed into an intravitreally injectable gel with 1x104 or 2x105 cells encapsulated in 2mg/ml type I collagen and 1% alginate. Gels with lower alginate concentration yielded higher initial cell viability but faster spheroid formation while increasing initial cell density encouraged cell growth. Continuous GDNF delivery was detected in culture and in healthy rat eyes for at least 14 days. The gels were well-tolerated with no host tissue attachment and contained living cell colonies. Most importantly, gel-implanted in dystrophic Royal College of Surgeons rat eyes for 28 days retained photoreceptors while those containing higher initial cell number yielded better photoreceptor survival. CAC ECT gels offers flexible system design and is a potential treatment option for posterior eye diseases.

  20. Sustained Delivery of Bioactive GDNF from Collagen and Alginate-Based Cell-Encapsulating Gel Promoted Photoreceptor Survival in an Inherited Retinal Degeneration Model.

    Science.gov (United States)

    Wong, Francisca S Y; Wong, Calvin C H; Chan, Barbara P; Lo, Amy C Y

    2016-01-01

    Encapsulated-cell therapy (ECT) is an attractive approach for continuously delivering freshly synthesized therapeutics to treat sight-threatening posterior eye diseases, circumventing repeated invasive intravitreal injections and improving local drug availability clinically. Composite collagen-alginate (CAC) scaffold contains an interpenetrating network that integrates the physical and biological merits of its constituents, including biocompatibility, mild gelling properties and availability. However, CAC ECT properties and performance in the eye are not well-understood. Previously, we reported a cultured 3D CAC system that supported the growth of GDNF-secreting HEK293 cells with sustainable GDNF delivery. Here, the system was further developed into an intravitreally injectable gel with 1x104 or 2x105 cells encapsulated in 2mg/ml type I collagen and 1% alginate. Gels with lower alginate concentration yielded higher initial cell viability but faster spheroid formation while increasing initial cell density encouraged cell growth. Continuous GDNF delivery was detected in culture and in healthy rat eyes for at least 14 days. The gels were well-tolerated with no host tissue attachment and contained living cell colonies. Most importantly, gel-implanted in dystrophic Royal College of Surgeons rat eyes for 28 days retained photoreceptors while those containing higher initial cell number yielded better photoreceptor survival. CAC ECT gels offers flexible system design and is a potential treatment option for posterior eye diseases. PMID:27441692

  1. All-solid-state proton battery using gel polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Kuldeep, E-mail: mishkuldeep@gmail.com [Department of Applied Science and Humanities, ABES Engineering College, Ghaziabad-201009, India and Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida-201307 (India); Pundir, S. S.; Rai, D. K. [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida-201307 (India)

    2014-04-24

    A proton conducting gel polymer electrolyte system; PMMA+NH{sub 4}SCN+EC/PC, has been prepared. The highest ionic conductivity obtained from the system is 2.5 × 10−4 S cm{sup −1}. The optimized composition of the gel electrolyte has been used to fabricate a proton battery with Zn/ZnSO{sub 4}⋅7H{sub 2}O anode and MnO{sub 2} cathode. The open circuit voltage of the battery is 1.4 V and the highest energy density is 5.7 W h kg−1 for low current drain.

  2. Investigation on poly (vinylidene fluoride) based gel polymer electrolytes

    Indian Academy of Sciences (India)

    S Rajendran; P Sivakumar; Ravi Shanker Babu

    2006-12-01

    An investigation is carried out on gel polymer electrolytes consisting of poly (vinylidene fluoride) (PVdF) as a host polymer, lithium perchlorate (LiClO4), lithium triflate (LiCF3SO3) as salts and mixture of ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. Polymer thin films were prepared by solvent casting technique and the obtained films were subjected to different characterizations, to confirm their structure, complexation and thermal changes. X-ray diffraction revealed that the salts and plasticizers disrupted the crystalline nature of PVdF based polymer electrolytes and converted them into an amorphous phase. TG/DTA studies showed the thermal stability of the polymer electrolytes. The role of interaction between polymer hosts on conductivity is discussed using the results of a.c. impedance studies. Room temperature (28°C) conductivity of 2.786 × 10-3 Scm-1 was observed in PVdF (24)–EC/PC (68)–LiCF3SO3 (2)/LiClO4 (6) polymer system.

  3. The fundamental radiation properties of normoxic polymer gel dosimeters: a comparison between a methacrylic acid based gel and acrylamide based gels

    International Nuclear Information System (INIS)

    Polymer gel dosimeters offer a wide range of applications in the three-dimensional verification of complex dose distributions such as in intensity-modulated radiotherapy. One of the major difficulties with polymer gel dosimeters is their sensitivity to oxygen, as oxygen inhibits the radiation-induced polymerization reaction. For several years, oxygen was removed from the gels by bubbling the sol with inert gases for several hours during the gel fabrication. Also, the gel had to be poured in containers with low oxygen permeability and solubility. Recently, it was found that these technical difficulties can easily be solved by adding an antioxidant to the gel. These gels are called 'normoxic' gels as they can be produced under normal atmospheric conditions. In this study several properties of polymer gel dosimeters have been investigated: the dose sensitivity, the temporal and spatial stability of the gel, the sensitivity of the dose response to temperature during irradiation and during MR imaging, the energy dependence and the dose-rate dependence. This study reveals that the normoxic polymer gel dosimeter based on methacrylic acid (nMAG) studied in this work has inferior radiation properties as compared to the polyacrylamide gelatine (PAG) gel dosimeters. It is shown that from the three different gel dosimeters investigated in this study, the nPAG gel dosimeter results in a less sensitive gel dosimeter but with superior radiation properties as compared to the nMAG gel dosimeter. The importance of investigating relevant radiation properties of gel dosimeters apart from the radiation sensitivity-prior to their use for dosimetric validation experiments-is illustrated and emphasized throughout this study. Other combinations of monomer and gelling agent may result in more reliable normoxic polymer gel dosimeters

  4. Surface structure of polymer Gels and emerging functions

    CERN Document Server

    Kobiki, Y

    1999-01-01

    We report the surface structure of polymer gels on a submicrometer scale during the volume phase transition. Sponge-like domains with a mesoscopic scale were directly observed in water by using at atomic force microscope (AFM). The surface structure characterized by the domains is discussed in terms of the root-mean-square roughness and the auto-correlation function, which were calculated from the AFM images. In order to demonstrate the role of surface structure in determining the macroscopic properties of film-like poly (N-isopropylacrylamide: NIPA) gels. It was found that the temperature dependence, as well as the absolute values of the static contact angle, were strongly dependent on the bulk network inhomogeneities. The relation between the mesoscopic structure and the macroscopic properties is qualitatively discussed in terms of not only the changes in the chemical, but also in the physical, surface properties of the NIPA gels in response to a temperature change.

  5. Imaging contrast effects in alginate microbeads containing trapped emulsion droplets.

    Science.gov (United States)

    Hester-Reilly, Holly J; Shapley, Nina C

    2007-09-01

    This study focuses on spherical microparticles made of cross-linked alginate gel and microcapsules composed of an oil-in-water emulsion where the continuous aqueous phase is cross-linked into an alginate gel matrix. We have investigated the use of these easily manufactured microbeads as contrast agents for the study of the flow properties of fluids using nuclear magnetic resonance imaging. Results demonstrate that combined spin-spin (T(2)) relaxation and diffusion contrast in proton NMR imaging can be used to distinguish among rigid polymer particles, plain alginate beads, and alginate emulsion beads. Multi-echo CPMG spin-echo imaging indicates that the average spin-lattice (T(1)) and spin-spin (T(2)) relaxation times of the plain alginate and alginate emulsion beads are comparable. Meanwhile, diffusion-weighted imaging produces sharp contrast between the two types of alginate beads, due to restricted diffusion inside the embedded oil droplets of the alginate emulsion beads. While the signal obtained from most materials is severely attenuated under applied diffusion gradients, the alginate emulsion beads maintain signal strength. The alginate emulsion beads were added to a suspension and imaged in an abrupt, annular expansion flow. The emulsion beads could be clearly distinguished from the surrounding suspending fluid and rigid polystyrene particles, through either T(2) relaxation or diffusion contrast. Such a capability allows future use of the alginate emulsion beads as tracer particles and as one particle type among many in a multimodal suspension where detailed concentration profiles or particle size separation must be quantified during flow. PMID:17600742

  6. Effects of alginate gel system on rheological and gel properties of hair-tail surimi%褐藻胶凝胶体系对带鱼鱼糜流变和凝胶特性的影响

    Institute of Scientific and Technical Information of China (English)

    刘鑫; 薛勇; 王超; 李兆杰; 薛长湖

    2011-01-01

    To improve the gel properties of hair-tail surimi,effects of alginate gel system on the rheological and gel properties of hair-taill surimi were determined by rheological analysis,texture analysis, whiteness, water holding capacity and microstructure. The results showed that: the storage modulus G' increased and damping factor decreased with addition of alginate gel system into the hair-tail surimi. The complex gel system became a stabilized gel 4h later. The storage modulus G' was decreased during heating process and was increased during temperature decreased. The storage modulus G' changed more obviously adding more alginate with the temperature changed. The gel strength of hair-tail surimi was increased with addition of alginate gel system. The breaking force was improved more obviously than the deformation. Results obtained from a trial gel produced confirmed that the values of grade A commercial surimi according to the optimization can be achieved. The optimized addition of alginate gel system was 1.56%~1.75%.%为了提高带鱼鱼糜凝胶特性,利用流变仪、质构仪、扫描电镜等方法研究了褐藻胶凝胶体系对带鱼鱼糜流变和凝胶特性的影响.结果表明:带鱼鱼糜在加入褐藻胶凝胶体系后,褐藻胶-鱼糜复合凝胶体系的储能模量G'增大,损耗因子tanδ减小,4h后达到平衡.最终所形成的复合凝胶是一种结构稳定的强凝胶.复合凝胶体系随着温度的升高,G'减小,加热后温度降低,G'增大.褐藻胶浓度越高,复合凝胶体系受温度变化影响越大.添加褐藻胶凝胶体系能够提高带鱼鱼糜的凝胶强度,其中破断强度受褐藻胶浓度的影响非常显著.对添加量进行优化后的结果表明,在褐藻胶添加量为1.56%~1.75%时,复合凝胶体系的凝胶强度和硬度均达到市售A级鱼糜的标准.

  7. Polymer sol-gel composite inverse opal structures.

    Science.gov (United States)

    Zhang, Xiaoran; Blanchard, G J

    2015-03-25

    We report on the formation of composite inverse opal structures where the matrix used to form the inverse opal contains both silica, formed using sol-gel chemistry, and poly(ethylene glycol), PEG. We find that the morphology of the inverse opal structure depends on both the amount of PEG incorporated into the matrix and its molecular weight. The extent of organization in the inverse opal structure, which is characterized by scanning electron microscopy and optical reflectance data, is mediated by the chemical bonding interactions between the silica and PEG constituents in the hybrid matrix. Both polymer chain terminus Si-O-C bonding and hydrogen bonding between the polymer backbone oxygens and silanol functionalities can contribute, with the polymer mediating the extent to which Si-O-Si bonds can form within the silica regions of the matrix due to hydrogen-bonding interactions.

  8. Uptake and Recovery of Lead by Agarose Gel Polymers

    Directory of Open Access Journals (Sweden)

    Anurag Pandey

    2009-01-01

    Full Text Available Problem statement: The uptake and recovery of lead ions were investigated by using agarose gel polymers. Approach: The experimental results showed that the agarose gel were effective in removing Pb (II from solution. Biosorption equilibrium was approached within 4 h. Pseudo second-order was applicable to all the sorption data over the entire time range. Results: The sorption data conformed well to both the Langmuir and the Freundlich isotherm model. The maximum adsorption capacity (qmax onto agarose gel was 115 mg g-1 for Pb (II. The maximum uptake of metal ions was obtained at pH 2.0. At temperature 35°C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. Conclusion: Elution experiments were carried out to remove Pb (II ions from loaded agarose gel and the bound metal ions could be eluted successfully using 0.1 M EDTA solution. The results suggest that agarose gel can be used as a biosorbent for an efficient removal of Pb(II ions from aqueous solution.

  9. Porous bioceramic bead prepared by calcium phosphate with sodium alginate gel and PE powder

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Y.C. [Department of Orthopaedic Surgery, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Ho, M.L.; Wu, S.C. [Department of Physiology, Kaohsiung Medical University, 100, Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China); Hsieh, H.S. [Faculty of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China); Wang, C.K. [Faculty of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Rd, Kaohsiung 807, Taiwan (China)], E-mail: ckwang@kmu.edu.tw

    2008-08-01

    The porous calcium phosphate beads were made by an alginate-interacting Ca ions mechanism on addition of a pore-forming polyethylene (PE) powder at 1250 deg. C sintering. The nature of the powders and porous beads were analyzed through X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR) and heavy metal analysis by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The porous beads size and the pore microstructure characteristics were determined using scanning electron microscopy (SEM). Beside, the porosity analysis was evaluated out using an Archimedes' principle and mercury porosimetry. Then, the sodium ampicillin was penetrated/adsorbed onto calcium-deficient hydroxyapatite porous beads, and was subsequently released in PBS. No matter whether the raw material was HAp, TCP or biphase, the Ca{sub 9}(HPO{sub 4})(PO{sub 4}){sub 5}OH phase (CDHA) was formed only after sintering. Porous beads of various calcium phosphates with different sizes (0.9-1.1 mm) and pore size groups (60-120 {mu}m and lower than 10 {mu}m) were appeared. The release kinetics of sodium ampicillin from these porous beads have indicated the possibility of using these materials as possible carriers for drug delivery.

  10. Gelation Behavior of Poly (Vinylidene Fluoride )-based Gel Polymer Electrolyte

    Institute of Scientific and Technical Information of China (English)

    WANG Biao-bing; GU Li-xia

    2006-01-01

    Poly ( vinylidene fluoride ) ( PVdF )-based gel polymer electrolytes with various compositions were prepared by solution casting technique. The kinetics of gelation was analyzed via the correlation between the apparent gelation rate and concentration of PVdF at a given temperature.Combination the results of the kinetics of gelation and the DSC study, it revealed that the phase separation was the major behavior and the fibrils were the major junction joints of the three-dimensional network even in the ease the concentration of PVdF was higher than 25 wt%. The porous surface observed by ESEM also reflected that the phase separation took place during the gelation.

  11. An Approach to Design and Development and Evaluation of Aceclofenac Floating Pellets Using Sodium Alginate and HPMC (HPMC K4M and HPMC K100LV as polymer

    Directory of Open Access Journals (Sweden)

    Umme Hani Khanam

    2013-10-01

    Full Text Available The present study was conducted to investigate the effect of Na-alginate and hydroxyl propyl methyl cellulose (HPMC polymer combination of Aceclofenac floating pellets. The Aceclofenac pellets were prepared with two different grades of HPMC polymers in the ratio of 2:1, 1:2 and 1.5:1.5 respectively while the amounts of Na-alginate used in the formulations was 3.50, 5.25 and 7.0g. Prepared pellets were evaluated by Particle size and Morphology, Contraction ratio, Moisture content, Friability Test, Swelling study, Buoyancy time and floating time of the pellets were examined on the basis of polymer concentration. The contraction ratio of the particle was highest when pellets were prepared with 1.5% Na- alginate solution and the polymer ratio was 1:2 (BX, BY, BZ. In case of Buoyancy of Pellets, When Alginate concentration was 1% and HPMC K4M and HPMC K100LV ratio was 2:1 then, the Aceclofenac pellets were not floated for long time. When the concentration of Na-Alginate increased to 1.5%, 2%, then all pellets were floated. In case of swelling study, CY, BZ, CZ showed highest swelling of approximately 8% when Na-alginate concentration was (1.5 % , 2%, 2 % and BY and CY batches showed lowest swelling of 2.9% at 4hrs when Na-alginate concentration was 1.5 %. Friability values for each formulation were recorded in table the values of the preferred formulas are within acceptable limit. Thus, the selection and use of suitable polymers in appropriate ratio is very important in designing floating pellets of Aceclofenac.

  12. Rapid Degradation of Phenanthrene by Using Sphingomonas sp. GY2B Immobilized in Calcium Alginate Gel Beads

    Directory of Open Access Journals (Sweden)

    Li-Ni Yang

    2009-09-01

    Full Text Available The strain Sphingomonas sp. GY2B is a high efficient phenanthrene-degrading strain isolated from crude oil contaminated soils that displays a broad-spectrum degradation ability towards PAHs and related aromatic compounds. This paper reports embedding immobilization of strain GY2B in calcium alginate gel beads and the rapid degradation of phenanthrene by the embedded strains. Results showed that embedded immobilized strains had high degradation percentages both in mineral salts medium (MSM and 80% artificial seawater (AS media, and had higher phenanthrene degradation efficiency than the free strains. More than 90% phenanthrene (100 mg·L-1 was degraded within 36 h, and the phenanthrene degradation percentages were >99.8% after 72 h for immobilized strains. 80% AS had significant negative effect on the phenanthrene degradation rate (PDR of strain GY2B during the linear-decreasing stage of incubation and preadsorption of cells onto rice straw could improve the PDR of embedded strain GY2B. The immobilization of strain GY2B possesses a good potential for application in the treatment of industrial wastewater containing phenanthrene and other related aromatic compounds.

  13. Formulation Development and Evaluation of Innovative Two-Polymer (SR-2P) Bioadhesive Vaginal Gel

    OpenAIRE

    Podaralla, Satheesh; Alt, Carsten; Shankar, Gita N.

    2014-01-01

    The main objective of this investigation was to study the feasibility of developing a vaginal bioadhesive microbicide using a SRI’s proprietary two-polymer gel platform (SR-2P). Several formulations were prepared with different combinations of temperature-sensitive polymer (Pluronic® F-127) and mucoadhesive polymer (Noveon® AA-1), producing gels of different characteristics. Prototype polymeric gels were evaluated for pH, osmolality, buffering capacity, and viscosity under simulated vaginal s...

  14. Drug–polymer interaction between glucosamine sulfate and alginate nanoparticles: FTIR, DSC and dielectric spectroscopy studies

    Science.gov (United States)

    El-Houssiny, A. S.; Ward, A. A.; Mostafa, D. M.; Abd-El-Messieh, S. L.; Abdel-Nour, K. N.; Darwish, M. M.; Khalil, W. A.

    2016-06-01

    This work involves the preparation and characterization of alginate nanoparticles (Alg NPs) as a new transdermal carrier for site particular transport of glucosamine sulfate (GS). The GS–Alg NPs were examined through transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and dielectric spectroscopy. GS–Alg NPs was efficiently prepared via ionic gelation method which generates favorable conditions for the entrapment of hydrophilic drugs. The TEM studies revealed that GS–Alg NPs are discrete and have spherical shapes. FTIR studies showed a spectral change of the characteristic absorptions bands of Alg NPs after encapsulation with GS because of the amine groups of GS and the carboxylic acid groups of Alg. The DSC data showed changes in the thermal behavior of GS–Alg NPs after the addition of GS indicating signs of main chemical interaction among the drug (GS) and the polymer (Alg). The absence of the drug melting endothermic peak within the DSC thermogram of GS–Alg NPs indicating that GS is molecularly dispersed in the NPs and not crystallize. From the dielectric study, it was found modifications within the dielectric loss (ε″) and conductivity (σ) values after the addition of GS. The ε″ and σ values of Alg NPs decreased after the addition of GS which indicated the successful encapsulation of GS within Alg NPs. Furthermore, the dielectric study indicated an increase of the activation energy and the relaxation time for the first process in the GS–Alg NPs as compared to Alg NPs. Consequently, the existing observations indicated an initiation of electrostatic interaction among the amine group of GS and carboxyl group of Alg indicating the successful encapsulation of GS inside Alg NPs which could provide favorable circumstance for the encapsulation of GS for topical management.

  15. Influence of adding Sea Spaghetti seaweed and replacing the animal fat with olive oil or a konjac gel on pork meat batter gelation. Potential protein/alginate association.

    Science.gov (United States)

    Fernández-Martín, F; López-López, I; Cofrades, S; Colmenero, F Jiménez

    2009-10-01

    Standard and modulated differential scanning calorimetry (DSC, MDSC) and dynamic rheological thermal analysis (DRTA) were used to in situ simulate the batter gelation process. Texture profile analysis (TPA) and conventional quality evaluations were applied to processed products. Sea Spaghetti seaweed addition was highly effective at reinforcing water/oil retention capacity, hardness and elastic modulus in all formulations. Olive oil substituting half pork fat yielded a presumably healthier product with slightly better characteristics than control. A konjac-starch mixed gel replacing 70% of pork fat produced a similar product to control but with nearly 10% more water. DSC revealed the currently unknown phenomenon that Sea Spaghetti alginates apparently prevented thermal denaturation of a considerable protein fraction. MDSC confirmed that this mainly concerned non-reversing effects, and displayed glass transition temperatures in the range of 55-65°C. DRTA and TPA indicated however much stronger alginate-type gels. It is tentatively postulated that salt-soluble proteins associate athermally with seaweed alginates on heating to constitute a separate phase in a thermal composite-gelling process.

  16. Olfaction Presentation System Using Odor Scanner and Odor-Emitting Apparatus Coupled with Chemical Capsules of Alginic Acid Polymer

    Science.gov (United States)

    Sakairi, Minoru; Nishimura, Ayako; Suzuki, Daisuke

    For the purpose of the application of odor to information technology, we have developed an odor-emitting apparatus coupled with chemical capsules made of alginic acid polymer. This apparatus consists of a chemical capsule cartridge including chemical capsules of odor ingredients, valves to control odor emission, and a temperature control unit. Different odors can be easily emitted by using the apparatus. We have developed an integrated system of vision, audio and olfactory information in which odor strength can be controlled coinciding with on-screen moving images based on analytical results from the odor scanner.

  17. Energy dependence of polymer gels in the orthovoltage energy range

    Directory of Open Access Journals (Sweden)

    Yvonne Roed

    2014-03-01

    Full Text Available Purpose: Ortho-voltage energies are often used for treatment of patients’ superficial lesions, and also for small- animal irradiations. Polymer-Gel dosimeters such as MAGAT (Methacrylic acid Gel and THPC are finding increasing use for 3-dimensional verification of radiation doses in a given treatment geometry. For mega-voltage beams, energy dependence of MAGAT has been quoted as nearly energy-independent. In the kilo-voltage range, there is hardly any literature to shade light on its energy dependence.Methods: MAGAT was used to measure depth-dose for 250 kVp beam. Comparison with ion-chamber data showed a discrepancy increasing significantly with depth. An over-response as much as 25% was observed at a depth of 6 cm.Results and Conclusion: Investigation concluded that 6 cm water in the beam resulted in a half-value-layer (HVL change from 1.05 to 1.32 mm Cu. This amounts to an effective-energy change from 81.3 to 89.5 keV. Response measurements of MAGAT at these two energies explained the observed discrepancy in depth-dose measurements. Dose-calibration curves of MAGAT for (i 250 kVp beam, and (ii 250 kVp beam through 6 cm of water column are presented showing significant energy dependence.-------------------Cite this article as: Roed Y, Tailor R, Pinksy L, Ibbott G. Energy dependence of polymer gels in the orthovoltage energy range. Int J Cancer Ther Oncol 2014; 2(2:020232. DOI: 10.14319/ijcto.0202.32 

  18. Responsive Gels with the Polymer Containing Alternating Naphthalene Diimide and Fluorinated Alkyl Chains: Gel Formation and Responsiveness as Well as Electrical Conductivity of Polymer Thin Films

    Institute of Scientific and Technical Information of China (English)

    罗河伟; 刘子桐; 蔡政旭; 吴刘锁; 张关心; 刘琛阳; 张德清

    2012-01-01

    A new electroactive polymer 1 with alternating NDI (naphthalene diimide) moieties and fluorinated alkyl chains was prepared and characterized. Gels of polymer 1 were formed in several solvents. Interestingly, gels of polymer 1 exhibited responsiveness toward N2H4, F and CN . Absorption and ESR spectroscopic studies revealed that such responsiveness is owing to the reduction of NDI moieties into the respective NDI'-. In addition, thin films of polymer 1 were easily prepared with spin-coating technique and the electrical conductivity of thin films reached 52.4 S/m after exposure to NeH4 vapor.

  19. Availability of a containerless polymer gel detector and a gelatin container

    International Nuclear Information System (INIS)

    We considered an availability of the polymer gel detector without container but with a plastic wrap under assumption of the low oxygen transmissivity of a sheet of plastic wrap. And a gelatin container was also examined for a gel detector. These samples can be made easily and this containerless polymer gel detector well works without any artifacts by means of wrapping with a thin plastic sheet. Nevertheless, there is still room for improvement on preventing oxygen contamination. Combination with a gelatin container and a polymer gel detector and/or Gafchromic films has a various potential for extension of 3D dosimetry

  20. Heavy metal adsorptivity of calcium-alginate-modified diethylenetriamine-silica gel and its application to a flow analytical system using flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Highlights: • Calcium-alginate-modified dien-silica gel adsorbed multivalent metal ions. • Metal ions adsorbed on CaAD were eluted using low acidic concentrations. • Flow system with CaAD-packed column enriched metal concentrations up to 50-fold. - Abstract: This study aimed to evaluate the heavy metal adsorptivity of calcium-alginate-modified diethylenetriamine-silica gel (CaAD) and incorporate this biosorbent into a flow analytical system for heavy metal ions using flame atomic absorption spectrometry (FAAS). The biosorbent was synthesized by electrostatically coating calcium alginate onto diethylenetriamine (dien)-silica gel. Copper ion adsorption tests by a batch method showed that CaAD exhibited a higher adsorption rate compared with other biosorbents despite its low maximum adsorption capacity. Next, CaAD was packed into a 1 mL microcolumn, which was connected to a flow analytical system equipped with an FAAS instrument. The flow system quantitatively adsorbed heavy metals and enriched their concentrations. This quantitative adsorption was achieved for pH 3–4 solutions containing 1.0 × 10−6 M of heavy metal ions at a flow rate of 5.0 mL min−1. Furthermore, the metal ions were successfully desorbed from CaAD at low nitric acid concentrations (0.05–0.15 M) than from the polyaminecarboxylic acid chelating resin (Chelex 100). Therefore, CaAD may be considered as a biosorbent that quickly adsorbs and easily desorbs analyte metal ions. In addition, the flow system enhanced the concentrations of heavy metals such as Cu2+, Zn2+, and Pb2+ by 50-fold. This new enrichment system successfully performed the separation and determination of Cu2+ (5.0 × 10−8 M) and Zn2+ (5.7 × 10−8 M) in a river water sample and Pb2+ (3.8 × 10−9 M) in a ground water sample

  1. Modeling studies: Adsorption of aniline blue by using Prosopis Juliflora carbon/Ca/alginate polymer composite beads.

    Science.gov (United States)

    Kumar, M; Tamilarasan, R

    2013-02-15

    The research article describes the experimental and modeling study for the adsorptive removal of aniline blue dye (AB dye) from aqueous matrices using a Prosopis Juliflora modified carbon/Ca/alginate polymer bead as a low cost and eco-friendly adsorbent. The rate of adsorption was investigated under various experimental parameters such as contact time, adsorbent dose, dye concentration, pH and temperature. The kinetics, equilibrium and thermodynamic studies were assessed to find out the efficiency of the adsorption process. The equilibrium uptake capacity of the adsorption process was found with Freundlich and Langmuir adsorption isotherm equations and it was evaluated by dimensionless separation factor (R(L)). The dynamics of adsorption was predicted by pseudo-first order, pseudo-second order Lagergren's equation and intra particle diffusion model. Adsorption feasibility was assessed with thermodynamic parameters such as isosteric heat of adsorption (ΔH°), standard entropy (ΔS°) and Gibbs free energy (ΔG°) using VantHoff plot. The alginate bead was characterized with FTIR spectroscopy and Scanning Electron Microscopy (SEM).

  2. Polymer gels with associating side chains and their interaction with surfactants

    Science.gov (United States)

    Gordievskaya, Yulia D.; Rumyantsev, Artem M.; Kramarenko, Elena Yu.

    2016-05-01

    Conformational behaviour of hydrophobically modified (HM) polymer gels in solutions of nonionic surfactants is studied theoretically. A HM gel contains hydrophobic side chains (stickers) grafted to its subchains. Hydrophobic stickers are capable to aggregate into joint micelles with surfactant molecules. Micelles containing more than one sticker serve as additional physical cross-links of the network, and their formation causes gel shrinking. In the proposed theoretical model, the interior of the gel/surfactant complex is treated as an array of densely packed spherical polymer brushes consisting of gel subchains tethered to the surface of the spherical sticker/surfactant micelles. Effect of stickers length and grafting density, surfactant concentration and hydrophobicity on gel swelling as well as on hydrophobic association inside it is analyzed. It is shown that increasing surfactant concentration can result in a gel collapse, which is caused by surfactant-induced hydrophobic aggregation of stickers, and a successive gel reswelling. The latter should be attributed to a growing fraction of surfactants in joint aggregates and, hence, increasing number of micelles containing only one sticker and not participating in gel physical cross-linking. In polyelectrolyte (PE) gels hydrophobic aggregation is opposed by osmotic pressure of mobile counterions, so that at some critical ionization degree hydrophobic association is completely suppressed. Hydrophobic modification of polymers is shown to open new ways for controlling gel responsiveness. In particular, it is discussed that incorporation of photosensitive groups into gel subchains and/or surfactant tail could give a possibility to vary the gel volume by light. Since hydrophobic aggregation regularities in gels and solutions are common, we hope our findings will be useful for design of polymer based self-healing materials as well.

  3. Multiple-phase behavior and memory effect of polymer gel

    CERN Document Server

    Annaka, M; Nakahira, T; Sugiyama, M; Hara, K; Matsuura, T

    2002-01-01

    A poly(4-acrylamidosalicylic acid) gel (PASA gel) exhibits multiple phases as characterized by distinct degrees of swelling; the gel can take one of four different swelling values, but none of the intermediate values. The gel has remarkable memory: the phase behavior of the gel depends on whether the gel has experienced the most swollen phase or the most collapsed phase in the immediate past. The information is stored and reversibly erased in the form of a macroscopic phase transition behavior. The structure factors corresponding to these four phases were obtained by SANS, which indicated the presence of characteristic structures depending on pH and temperature, particularly in the shrunken state. (orig.)

  4. Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Chen [ORNL; Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL

    2013-01-01

    Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

  5. Effect of Oxygen and Bacteria on the Property of Polymer Gel

    Institute of Scientific and Technical Information of China (English)

    Weidong Jiang; Xiangguo Lu; Xinxia Xu

    2007-01-01

    The viscosity property of Cr3+, Al3+, and compound ion cross-linked polymer gel solution in the anaerobic and aerobic environment was investigated aiming at meeting the practical demand of the oil field. The viscosity reserving effect after adding the biocide and the gelation in the anaerobic and aerobic environments was also studied in the paper. The results indicate that the viscosity of the cross-linked polymer gel solution caused by the water produced in aerobic environment is higher than that in anaerobic environment, and that the viscosity value of the cross-linked polymer gel solutions after adding biocides has improved to some extent and polymer gel has gelated well in anaerobic environment.

  6. Diffusion of Acetic Acid Across Oil/Water Interface in Emulsification-Internal Gelation Process for Preparation of Alginate Gel Beads

    Institute of Scientific and Technical Information of China (English)

    LIU Xiu-dong; YU Wei-ting; LIN Jun-zhang; MA Xiao-jun; YUAN Quan

    2007-01-01

    Alginate has been widely used in cell microencapsulation and drug delivery systems in the form of gel beads or microcapsules. Although an alternative novel emulsification-internal gelation technology has been established and both the properties and the potential applications of the beads in drug delivery systems have been studied, the mechanism has not been well understood compared with the traditional droplet method( external gelation technology). On the basis of our previous knowledge that the novel technology is composed of complicatedly consecutive processes with multistep diffusion and re action, and the diffusion of acetic acid across oil/water interface being the prerequisite that determines the occurrence and rate for the reactions and the structures and properties of final produced gel beads, a special emphasis was placed on the diffusion process. With the aid of diffusion modeling and simple experimental design, the diffusion rate constant and diffusion coefficient of acetic acid across oil/water interface were determined to be in the orders of magnitude of 10-6 and 10-16, respectively. This knowledge will be of particular importance in understanding and interpreting the formation, structure of the gel beads and the relationship between the structure and properties and guiding the preparation and quality control of the gel beads.

  7. "JCE" Classroom Activity Connections: NaCl or CaCl[subscript 2], Smart Polymer Gel Tells More

    Science.gov (United States)

    Chen, Yueh-Huey; Lin, Jia-Ying; Wang, Yu-Chen; Yaung, Jing-Fun

    2010-01-01

    This classroom activity connection demonstrates the differences between the effects of NaCl (a salt of monovalent metal ions) and CaCl[subscript 2] (a salt of polyvalent metal ions) on swollen superabsorbent polymer gels. Being ionic compounds, NaCl and CaCl[subscript 2] both collapse the swollen polymer gels. The gel contracted by NaCl reswells…

  8. A HYBRID POLYMER GEL AND ITS STATIC NONERGODICIT

    Institute of Scientific and Technical Information of China (English)

    Yue Zhao; Chi Wu

    2002-01-01

    We used a thermally reversible hybrid gel made of billions of physically jam-packed swollen thermally sensitive poly(N-isopropyl-acrylamide) chemical microgels. Laser light scattering study on a series of such hybrid gels formed at different gelling rates and temperatures revealed that the position-dependence of the scattering speckle pattern (static nonergodicity) came from large voids formed during the sol-gel transition. With a proper preparation, such a nonergodicity could be completely removed, indicating that the static nonergodicity generally observed in a gel is not intrinsic, but comes from the clustering "island" structure formed during the gelation process.

  9. Associative polymers and physical gels derived from natural biopolymers; Polymeres associes et gels physiques derives de biopolymeres naturels

    Energy Technology Data Exchange (ETDEWEB)

    Muller, G.; Huguet, J.; Merle, L.; Grisel, M.; Picton, L.; Bataille, I.; Charpentier, D.; Glinel, K. [CNRS, Polymeres, Biopolymeres et Membranes, Universite de Rouen, 76 - Mont-Saint-Aignan (France)

    1997-04-01

    Polymers are largely used in oil-field operations where the control of rheology of aqueous phases ids of primary importance. Polymers systems showing high viscosity present many advantages as candidates for drilling muds. Associating polymers, i.e. polymers the hydrophilic main chains of which have been properly modified by introducing hydrophobic groups and weak physical ges are good examples of such systems. The different systems chosen to be studied are derived from natural biopolymers. They are: Alkyl derivatives issued from neutral (HEC) and ionic (CMC) cellulosic ether derivatives; alkyl and fluoro alkyl derivatives from neutral (Pull) and ionic (CMP) bacterial polysaccharide pullulane; weak physical gels resulting from complex formation between borate ions and the neutral fungal polysaccharide schizophyllan. The different results are given in tables and figures. (N.C.)

  10. Polymer composite principles applied to hair styling gels.

    Science.gov (United States)

    Wade Rafferty, Denise; Zellia, Joseph; Hasman, Daniel; Mullay, John

    2008-01-01

    A novel approach is taken to understand the mechanical performance of fixative-treated hair tresses. Polymer composite principles are applied to explain the performance. Examples are given for polyacrylate-2 crosspolymer that show that the choice of neutralizer affects the film properties of anionic acrylic polymers by plasticization or by hardening through ionic (physical) crosslinking. The effect of these changes in the polymer film on the composite properties was determined by mechanical stiffness and high-humidity curl retention testing. It is shown that both adhesion to the hair and polymer cohesion are important in determining fixative polymer performance. The implications of the results for the formulation of fixative systems are discussed.

  11. Interaction of Green Polymer Blend of Modified Sodium Alginate and Carboxylmethyl Cellulose Encapsulation of Turmeric Extract

    Directory of Open Access Journals (Sweden)

    Sa-Ad Riyajan

    2013-01-01

    Full Text Available Turmeric extract (tmr loaded nanoparticles were prepared by crosslinking modified carboxylmethyl cellulose (CMC and modified sodium alginate (SA with calcium ions, in a high pressure homogenizer. The FTIR spectra of CMC and SA were affected by blending due to hydrogen bonding. The negative zeta potential increased in magnitude with CMC content. The smallest nanoparticles were produced with a 10 : 5 SA/CMC blend. Also the release rates of the extract loading were measured, with model fits indicating that the loading level affected the release rate through nanoparticle structure. The 10 : 5 SA/CMC blend loading with tmr and pure tmr showed a good % growth inhibition of colon cancer cells which indicate that tmr in the presence of curcumin in tmr retains its anticancer activity even after being loaded into SA/CMC blend matrix.

  12. Differentiation of adipose-derived stem cells toward nucleus pulposuslike cells induced by hypoxia and a three-dimensional chitosan-alginate gel scaffold in vitro

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhicheng; Li Fang; Tian Haiquan; Guan Kai; Zhao Guangmin; Shan Jianlin; Ren Dajiang

    2014-01-01

    Background Injectable three-dimensional (3D) scaffolds have the advantages of fluidity and moldability to fill irregularshaped defects,simple incorporation of bioactive factors,and limited surgical invasiveness.Adipose-derived stem cells (ADSCs) are multipotent and can be differentiated toward nucleus pulposus (NP)-Iike cells.A hypoxic environment may be important for differentiation to NP-like cells because the intervertebral disc is an avascular tissue.Hence,we investigated the induction effects of hypoxia and an injectable 3D chitosan-alginate (C/A) gel scaffold on ADSCs.Methods The C/A gel scaffold consisted of medical-grade chitosan and alginate.Gel porosity was calculated by liquid displacement method.Pore microstructure was analyzed by light and scanning electron microscopy.ADSCs were isolated and cultured by conventional methods.Passage 2 BrdU-labeled ADSCs were co-cultured with the C/A gel.ADSCs were divided into three groups (control,normoxia-induced,and hypoxia-induced groups).In the control group,cells were cultured in 10% FBS/DMEM.Hypoxia-induced and normoxia-induced groups were induced by adding transforming growth factor-β1,dexamethasone,vitamin C,sodium pyruvate,proline,bone morphogenetic protein-7,and 1% ITS-plus to the culture medium and maintaining in 2% and 20% O2,respectively.Histological and morphological changes were observed by light and electron microscopy.ADSCs were characterized by flow cytometry.Cell viability was investigated by BrdU incorporation.Proteoglycan and type Ⅱ collagen were measured by safranin O staining and the Sicool method,respectively.mRNA expression of hypoxia-inducing factor-1α (HIF-1α),aggrecan,and Type Ⅱ collagen was determined by reverse transcription-polymerase chain reaction.Results C/A gels had porous exterior surfaces with 80.57% porosity and 50-200 μm pore size.Flow cytometric analysis of passage 2 rabbit ADSCs showed high CD90 expression,while CD45 expression was very low.The morphology of

  13. A study of normoxic polymer gel using monomer 2-hydroxyethyl methacrylate (HEMA)

    Energy Technology Data Exchange (ETDEWEB)

    Ishak, Siti Atiqah; Mustafa, Iskandar Shahrim; Rahman, Azhar Abdul [School of Physics, Universiti Sains Malaysia, Pulau Pinang (Malaysia); Moktar, Mohd; Min, Ung Ngie [Radiotherapy Department, University Malaya Medical Centre, Kuala Lumpur (Malaysia)

    2015-04-24

    The aim of this study is to determine the sensitivity of HEMA-polymer gel mixture consist of monomer 2-hydroxyethyl methacrylate (HEMA) with different types of composition. Several composition of HEMA-polymer gel were fabricated and the gels were irradiated with radiation dose between 10 cGy to 100cGy by using x-ray machine and 100 cGy to 1400 cGy by using 6 MV photon beam energy of linear accelerator. The degree of polymerization was evaluated by using magnetic resonance imaging (MRI) with dependence of R2-dose response. Polymer gel consists of cross-linker, anti-oxidant Tetrakis(Hydroxymethyl)phosphonium chloride solution (THPC) and oxygen scavenger hydroquinone shows a stable sensitivity with highest dose dependency. Besides, the results shows the stage polymerization consist of induction, propagation, termination, and chain transfer were dependence with type of chemical mixture and radiation dose. Thus, normoxic HEMA-polymer gel with the different gel formulations can have a better dose resolution and an appropriate recipe must be selected to increase of the sensitivity required and the stability of the dosimeter.

  14. Stable Lithium Deposition Generated from Ceramic-Cross-Linked Gel Polymer Electrolytes for Lithium Anode.

    Science.gov (United States)

    Tsao, Chih-Hao; Hsiao, Yang-Hung; Hsu, Chun-Han; Kuo, Ping-Lin

    2016-06-22

    In this work, a composite gel electrolyte comprising ceramic cross-linker and poly(ethylene oxide) (PEO) matrix is shown to have superior resistance to lithium dendrite growth and be applicable to gel polymer lithium batteries. In contrast to pristine gel electrolyte, these nanocomposite gel electrolytes show good compatibility with liquid electrolytes, wider electrochemical window, and a superior rate and cycling performance. These silica cross-linkers allow the PEO to form the lithium ion pathway and reduce anion mobility. Therefore, the gel not only features lower polarization and interfacial resistance, but also suppresses electrolyte decomposition and lithium corrosion. Further, these nanocomposite gel electrolytes increase the lithium transference number to 0.5, and exhibit superior electrochemical stability up to 5.0 V. Moreover, the lithium cells feature long-term stability and a Coulombic efficiency that can reach 97% after 100 cycles. The SEM image of the lithium metal surface after the cycling test shows that the composite gel electrolyte with 20% silica cross-linker forms a uniform passivation layer on the lithium surface. Accordingly, these features allow this gel polymer electrolyte with ceramic cross-linker to function as a high-performance lithium-ionic conductor and reliable separator for lithium metal batteries. PMID:27247991

  15. A flexible Li polymer primary cell with a novel gel electrolyte based on poly(acrylonitrile)

    Science.gov (United States)

    Akashi, Hiroyuki; Tanaka, Ko-ichi; Sekai, Koji

    The performance of a Li polymer primary cell with fire-retardant poly(acrylonitrile) (PAN)-based gel electrolytes is reported. By optimizing electrodes, electrolytes, the packaging material, and the structural design of the polymer cell, we succeeded in developing a "film-like" Li polymer primary cell with sufficient performance for practical use. The cell is flexible and less than 0.5 mm thick, which makes it suitable for a power source for some smart devices, such as an IC card. Fast cation conduction in the gel electrolyte minimizes the drop of the discharge capacity even at -20 °C. The high chemical stability of the gel electrolytes and the new packaging material allow the self-discharge rate to be limited to under 4.3%, which is equivalent to that of conventional coin-shaped or cylindrical Li-MnO 2 cells.

  16. Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

    Science.gov (United States)

    Cao, Zi-Quan; Wang, Guo-Jie

    2016-06-01

    Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here. PMID:27153184

  17. Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

    Science.gov (United States)

    Cao, Zi-Quan; Wang, Guo-Jie

    2016-06-01

    Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here.

  18. Investigation of optimal scanning protocol for X-ray computed tomography polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Sellakumar, P. [Bangalore Institute of Oncology, 44-45/2, II Cross, RRMR Extension, Bangalore 560 027 (India)], E-mail: psellakumar@rediffmail.com; James Jebaseelan Samuel, E. [School of Science and Humanities, VIT University, Vellore 632 014 (India); Supe, Sanjay S. [Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Hosur Road, Bangalore 560 027 (India)

    2007-11-15

    X-ray computed tomography is one of the potential tool used to evaluate the polymer gel dosimeters in three dimensions. The purpose of this study is to investigate the factors which affect the image noise for X-ray CT polymer gel dosimetry. A cylindrical water filled phantom was imaged with single slice Siemens Somatom Emotion CT scanner. The imaging parameters like tube voltage, tube current, slice scan time, slice thickness and reconstruction algorithm were varied independently to study the dependence of noise on each other. Reductions of noise with number of images to be averaged and spatial uniformity of the image were also investigated. Normoxic polymer gel PAGAT was manufactured and irradiated using Siemens Primus linear accelerator. The radiation induced change in CT number was evaluated using X-ray CT scanner. From this study it is clear that image noise is reduced with increase in tube voltage, tube current, slice scan time, slice thickness and also reduced with increasing the number of images averaged. However to reduce the tube load and total scan time, it was concluded that tube voltage of 130 kV, tube current of 200 mA, scan time of 1.5 s, slice thickness of 3 mm for high dose gradient and 5 mm for low dose gradient were optimal scanning protocols for this scanner. Optimum number of images to be averaged was concluded to be 25 for X-ray CT polymer gel dosimetry. Choice of reconstruction algorithm was also critical. From the study it is also clear that CT number increase with imaging tube voltage and shows the energy dependency of polymer gel dosimeter. Hence for evaluation of polymer gel dosimeters with X-ray CT scanner needs the optimization of scanning protocols to reduce the image noise.

  19. Investigation of optimal scanning protocol for X-ray computed tomography polymer gel dosimetry

    International Nuclear Information System (INIS)

    X-ray computed tomography is one of the potential tool used to evaluate the polymer gel dosimeters in three dimensions. The purpose of this study is to investigate the factors which affect the image noise for X-ray CT polymer gel dosimetry. A cylindrical water filled phantom was imaged with single slice Siemens Somatom Emotion CT scanner. The imaging parameters like tube voltage, tube current, slice scan time, slice thickness and reconstruction algorithm were varied independently to study the dependence of noise on each other. Reductions of noise with number of images to be averaged and spatial uniformity of the image were also investigated. Normoxic polymer gel PAGAT was manufactured and irradiated using Siemens Primus linear accelerator. The radiation induced change in CT number was evaluated using X-ray CT scanner. From this study it is clear that image noise is reduced with increase in tube voltage, tube current, slice scan time, slice thickness and also reduced with increasing the number of images averaged. However to reduce the tube load and total scan time, it was concluded that tube voltage of 130 kV, tube current of 200 mA, scan time of 1.5 s, slice thickness of 3 mm for high dose gradient and 5 mm for low dose gradient were optimal scanning protocols for this scanner. Optimum number of images to be averaged was concluded to be 25 for X-ray CT polymer gel dosimetry. Choice of reconstruction algorithm was also critical. From the study it is also clear that CT number increase with imaging tube voltage and shows the energy dependency of polymer gel dosimeter. Hence for evaluation of polymer gel dosimeters with X-ray CT scanner needs the optimization of scanning protocols to reduce the image noise

  20. Gel Formation in Polymers Undergoing Radiation-Induced Crosslinking and Scission

    DEFF Research Database (Denmark)

    Handlos, V. N.; Singer, Klaus Albert Julius

    1976-01-01

    A study was made of the solubility of irradiated polyethylene. The experimental data were treated according to the Saito-Inokuti theory for gel formation in polymers exposed to ionizing radiation. Among other things, this theory is based upon the molecular weight distribution of the unirradiated...... polymer; in the present work, the actual distributions were determined by high-temperature gel permeation chromatography and corrected for long-chain branching. Under these circumstances, good agreement between theory and experimental data was obtained, which allowed the determination of the radiation...

  1. Formulation development and evaluation of innovative two-polymer (SR-2P) bioadhesive vaginal gel.

    Science.gov (United States)

    Podaralla, Satheesh; Alt, Carsten; Shankar, Gita N

    2014-08-01

    The main objective of this investigation was to study the feasibility of developing a vaginal bioadhesive microbicide using a SRI's proprietary two-polymer gel platform (SR-2P). Several formulations were prepared with different combinations of temperature-sensitive polymer (Pluronic® F-127) and mucoadhesive polymer (Noveon® AA-1), producing gels of different characteristics. Prototype polymeric gels were evaluated for pH, osmolality, buffering capacity, and viscosity under simulated vaginal semen dilutions, and bioadhesivity using ex vivo mini pig vaginal tissues and texture analyzer. The pH of the polymeric gel formulations ranged from 5.1 to 6.4; the osmolality varied from 13 to 173 mOsm. Absolute viscosity ranged from 513 to 3,780 cPs, and was significantly reduced (1.5- to 3-fold) upon incubation with simulated vaginal and semen fluid mixture. Among the tested gels (indicated in the middle row as a molar ratio of a mixture of Noveon vs. Pluronic), only SR-2P retained gel structure upon dilution with simulated fluids and mild simulated coital stress. The pH of the SR-2P gel was maintained at about 4.6 in simulated vaginal fluid and also showed high peak force of adhesion in mini pig vaginal tissue. Furthermore, SR-2P gel caused no or only minimal irritation in a mouse vaginal irritation model. The results of this preliminary study demonstrated the potential application of SR-2P gel as a vaginal microbicide vehicle for delivery of anti-HIV agents. PMID:24781671

  2. Alginate Nanoparticles as a Promising Adjuvant and Vaccine Delivery System

    Directory of Open Access Journals (Sweden)

    F Sarei

    2013-01-01

    Full Text Available During last decades, diphtheria has remained as a serious disease that still outbreaks and can occur worldwide. Recently, new vaccine delivery systems have been developed by using the biodegradable and biocompatible polymers such as alginate. Alginate nanoparticles as a carrier with adjuvant and prolong release properties that enhance the immunogenicity of vaccines. In this study diphtheria toxoid loaded nanoparticles were prepared by ionic gelation technique and characterized with respect to size, zeta potential, morphology, encapsulation efficiency, release profile, and immunogenicity. Appropriate parameters (calcium chloride and sodium alginate concentration, homogenization rate and homogenization time redounded to the formation of suitable nanoparticles with a mean diameter of 70±0.5 nm. The loading studies of the nanoparticles resulted in high loading capacities (>90% and subsequent release studies showed prolong profile. The stability and antigenicity of toxoid were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and ouchterlony test and proved that the encapsulation process did not affect the antigenic integrity and activity. Guinea pigs immunized with the diphtheria toxoid-loaded alginate nanoparticles showed highest humoral immune response than conventional vaccine. It is concluded that, with regard to the desirable properties of nanoparticles and high immunogenicity, alginate nanoparticles could be considered as a new promising vaccine delivery and adjuvant system.

  3. Dosimetric evaluation of a novel polymer gel dosimeter for proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zeidan, O. A.; Sriprisan, S. I.; Lopatiuk-Tirpak, O.; Kupelian, P. A.; Meeks, S. L.; Hsi, W. C.; Li, Z.; Palta, J. R.; Maryanski, M. J. [M. D. Anderson Cancer Center Orlando, Orlando, Florida 32806 (United States); University of Florida Proton Therapy Institute, Jacksonville, Florida 32206 (United States); MGS Research, Inc., Madison, Connecticut 06443 (United States)

    2010-05-15

    Purpose: The aim of this study is to evaluate the dosimetric performance of a newly developed proton-sensitive polymer gel formulation for proton therapy dosimetry. Methods: Using passive scattered modulated and nonmodulated proton beams, the dose response of the gel was assessed. A next-generation optical CT scanner is used as the readout mechanism of the radiation-induced absorbance in the gel medium. Comparison of relative dose profiles in the gel to ion chamber profiles in water is performed. A simple and easily reproducible calibration protocol is established for routine gel batch calibrations. Relative stopping power ratio measurement of the gel medium was performed to ensure accurate water-equivalent depth dose scaling. Measured dose distributions in the gel were compared to treatment planning system for benchmark irradiations and quality of agreement is assessed using clinically relevant gamma index criteria. Results: The dosimetric response of the gel was mapped up to 600 cGy using an electron-based calibration technique. Excellent dosimetric agreement is observed between ion chamber data and gel. The most notable result of this work is the fact that this gel has no observed dose quenching in the Bragg peak region. Quantitative dose distribution comparisons to treatment planning system calculations show that most (>97%) of the gel dose maps pass the 3%/3 mm gamma criterion. Conclusions: This study shows that the new proton-sensitive gel dosimeter is capable of reproducing ion chamber dose data for modulated and nonmodulated Bragg peak beams with different clinical beam energies. The findings suggest that the gel dosimeter can be used as QA tool for millimeter range verification of proton beam deliveries in the dosimeter medium.

  4. Polymer Physics Prize: Designing ''Materials that Compute'': Exploiting the Properties of Self-oscillating Polymer Gels

    Science.gov (United States)

    Balazs, Anna

    Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of ''materials that compute'', we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. The oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling ''materials that compute''.

  5. FORMULATION AND EVALUATION OF FLOATING IN SITU GEL BASED GASTRO RETENTIVE DRUG DELIVERY OF CIMETIDINE

    OpenAIRE

    Bhargav D. Jayswal; Varun T. Yadav; Kunal N. Patel; Bhavana A. Patel; Poras A. Patel

    2012-01-01

    The present investigation deals with the formulation and evaluation of sodium alginate and pectin basedIn situ gel of Cimetidine. Sodium alginate and pectin were used as a polymer and CaCO3 was used as across-linking agent. In-situ forming polymeric formulations drug delivery systems is in sol form beforeadministration in the body, but once administered, undergoes gelation in-situ to form a gel. Theformulation of gel depends upon factors like temperature modulation, pH changes, presence of io...

  6. A superoxide anion biosensor based on direct electron transfer of superoxide dismutase on sodium alginate sol–gel film and its application to monitoring of living cells

    International Nuclear Information System (INIS)

    Highlights: ► The direct electron transfer of SOD was facilitated on SA sol–gel film. ► O2·− sensor has high selectivity, stability and sensitivity. ► The proposed measurement for O2·− can be applied in living cells. - Abstract: The direct electron transfer of superoxide dismutase (SOD) was greatly facilitated by sodium alginate (SA) sol–gel film with the formal potential of 0.14 V, which was just located between O2·−/O2 and O2·−/H2O2. The preparation of the SOD/SA modified electrode was simple without any mediators or promoters. Based on bimolecular recognition for specific reactivity of SOD/SA toward O2·−, the SOD modified electrode was utilized to measure O2·− with good analytical performance, such as low applied potential (0 V), high selectivity (no obvious interference), wide linear range (0.44–229.88 μM) and low detection limit (0.23 μM) in pH 7.0 phosphate buffer solution. Furthermore, it could be successfully exploited for the determination of O2·− released from living cells directly adhered on the modified electrode surface. Thus, the proposed O2·− biosensor, combining with the properties of SA sol–gel film, provided a novel approach for protein immobilization, direct electron transfer study of the immobilized protein and real-time determination of O2·− released from living cells.

  7. Hemoglobin-imprinted polymer gel prepared using modified glucosamine as functional monomer

    Institute of Scientific and Technical Information of China (English)

    Hai Li Zhao; Tian Ying Guo; Yong Qing Xia; Mou Dao Song

    2008-01-01

    A new functional glycomonomer was obtained from modified glucosamine.Hemoglobin-imprinted polymer gel was prepared with allyl-bromide modified glucosamine as functional monomer,poly(ethylene-glycol)diaorylate(PEGDA)as cross-linker and ammonium persulfate[(NH4)2S2O8]/sodium hydrogen sulfite(NaHSO3)as initiators in a phosphate buffer.The adsorption capacity and selective adsorption of the molecular imprinting polymer(MIP)were also discussed.

  8. Sensitivity calibration procedures in optical-CT scanning of BANG®3 polymer gel dosimeters

    OpenAIRE

    Xu, Y; Wuu, Cheng-Shie; Maryanski, Marek J.

    2010-01-01

    The dose response of the BANG®3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS™ laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurem...

  9. Feasibility of quantitative PET/CT dosimetry for proton therapy using polymer gels

    Energy Technology Data Exchange (ETDEWEB)

    Zeidan, O A; Hsi, W C; Lopatiuk-Tirpak, O; Sriprisan, S I; Meeks, S L; Kupelian, P A; Li, Z; Palta, J R, E-mail: lenatirpak@gmail.co

    2010-11-01

    A feasibility study of proton beam PET/CT off-line quantitative dosimetry using polymer gels is presented. A newly developed proton-sensitive polymer gel dosimeter (BANG( (registered)) 3-Pro2) is used as a dosimeter and a tissue-equivalent phantom medium for this study. We explore a new approach to correlating measured proton 3-dimensional (3D) dose distributions directly to measured positron emission from in the gel medium using PET/CT imaging. A large cylindrical volume (2.2 Litres) of the gel was irradiated with a clinical modulated proton beam using irregular-shaped aperture geometry. The gel was imaged in a nearby PET/CT unit immediately (<3 min) after irradiation. Dose distribution in the gel was generated using an optical tomography scanning system. Direct 3D spatial comparison of dose and positron emission distributions was then performed. Profiles along the beam path show that the distal fall-off of the dose is nearly 2 cm deeper than the activity profile which is comparable to previous studies with plastic phantoms and Monte Carlo simulations of activity distributions. Planar PET and dose distributions at depth and perpendicular to beam axis show a strong one-to-one spatial correlation. This phantom study demonstrates that the gel medium could be potentially useful for quantifying various physical factors that can influence the PET activity range verification method in patients.

  10. DEVELOPMENT OF POLYMER GEL SYSTEMS TO IMPROVE VOLUMETRIC SWEEP AND REDUCE PRODUCING WATER/OIL RATIOS

    Energy Technology Data Exchange (ETDEWEB)

    G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Rajeev Jain; Tuan Nguyen

    2003-11-01

    Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of the first year of a three-year research program that is aimed at the understanding of the chemistry of gelation and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work has focused on a widely-applied system in field applications, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. The initial reaction between chromium acetate and one polymer is referred to as the uptake reaction. The uptake reaction was studied as functions of chromium and polymer concentrations and pH values. Experimental data were regressed to determine a rate equation that describes the uptake reaction of chromium by polyacrylamide. Pre-gel aggregates form and grow as the reactions between chromium acetate and polyacrylamide proceed. A statistical model that describes the growth of pre-gel aggregates was developed using the theory of branching processes. The model gives molecular weight averages that are expressed as functions of the conversion of the reactive sites on chromium acetate or on the polymer molecule. Results of the application of the model correlate well with experimental data of viscosity and weight-average molecular weight and gives insights into the gelation process. A third study addresses the flow of water and oil in rock material after a gel treatment. Previous works have shown that gel treatments usually reduce the permeability to water to a greater extent than the permeability to oil is reduced. This phenomenon is referred to as disproportionate permeability reduction (DPR). Flow experiments were conducted to determine the effect of polymer and chromium concentrations on

  11. Fracturing Fluid (Guar Polymer Gel Degradation Study by using Oxidative and Enzyme Breaker

    Directory of Open Access Journals (Sweden)

    Aung Kyaw

    2012-06-01

    Full Text Available Oxidative and enzyme breakers are used in this research project with the main objective to study on the degradation pattern of fracturing fluid (i.e., guar polymer gel as a function of time, temperature and breaker concentration itself. The fracturing fluid used in hydraulic fracturing or frac pack contain a chemical breakers to reduce the viscosity of the fluid intermingled with the proppant. Chemical breakers reduce viscosity of the guar polymer by cleaving the polymer into small-molecular-weight fragments. The reduction of viscosity will facilitate the flow-back of residual polymer providing rapid recovery of polymer from proppant pack. Ineffective breakers or misapplication of breakers can result in screen-outs or flow-back of viscous fluids both of which can significantly decrease the well productivity. Breaker activity of low to medium temperature range oxidative and enzyme breaker systems was evaluated. ViCon NF an oxidative breaker (Halliburton product and GBW 12- CD an enzyme breaker (BJ Services product were used in this research project with the main objective to study on the degradation pattern of fracturing fluid (guar polymer gel as a function of (time, temperature and breaker concentration itself. This study provides focuses on the way to mix the fracturing fluid, compositions of the fracturing fluid and how to conduct the crosslink and break test. Crosslink test indicate the optimum cross-linker concentration to produce good crosslink gel and the break test gave the characteristic of the gel during degradation process and also the break time. Besides relying on the laboratory experiment, information obtained from research on SPE and US Pattern papers were used to make a comparison study on oxidative and enzyme breakers properties. Degradation pattern observed from the break test showed that reduction in gel viscosity depends on time, temperature and breaker concentration. Observations from experiment also revealed that small

  12. A novel and high-effective redox-mediated gel polymer electrolyte for supercapacitor

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Alkali and P-phenylenediamine doped polyvinyl alcohol gel electrolyte is prepared. • The PVA-KOH-PPD gel electrolyte can also be used as separator. • The introduction of PPD increases the ionic conductivity of electrolyte. • The supercapacitor exhibits flexible and high energy density. - Abstract: A supercapacitor utilize a novel redox-mediated gel polymer (PVA-KOH-PPD) as electrolyte and separator, and activated carbon as electrodes is assembled. The PVA-KOH-PPD gel polymer as potential electrolyte for supercapacitor is investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. It is found that the supercapacitor exhibits high ionic conductivity (25 mS cm−1), large electrode specific capacitance (611 F g−1) and high energy density (82.56 Wh kg−1). The high performance is attributed to the addition of quick redox reactions at the electrolyte|electrode interface as PPD undergoes a two-proton/two-electron reduction and oxidation during cycling. Furthermore, the supercapacitor with PVA-KOH-PPD gel polymer shows excellent charge-discharge stability, after 1000 charge-discharge cycles, the supercapacitor still retains a high electrode specific capacitance of 470 F g−1. It is believed that the idea using redox mediator has a good prospect for improving the performances of supercapacitors

  13. Interpretation of mucoadhesive properties of polymer gel preparations using a tensile strength method.

    Science.gov (United States)

    Hägerström, H; Edsman, K

    2001-12-01

    We have developed a new tensile strength method for assessing mucoadhesive properties of polymer gels utilising freshly excised porcine nasal mucosa and a texture analyser. In conjunction with this, we propose a method for interpreting the mucoadhesive properties that is based on reasoning about the locus of the failure of a mucoadhesive joint. This involves measuring the cohesiveness of the gel and the mucus layer, respectively, and comparing these results with those obtained from a mucoadhesion measurement. Linear polymers (sodium carboxymethylcellulose, poly(acrylic acid) and sodium hyaluronate) and a cross-linked polymer (poly(acrylic acid)) were used as model polymers in this study. It was shown that the withdrawal speed of the probe should be low, about 0.1 mm s(-1), and that a contact time of 2 min was sufficient. In the mucoadhesion measurements there was no dependence of the results on the contact time in the interval 2-20 min. The tensile work appeared to be more applicable than the fracture strength for interpreting mucoadhesive properties. Furthermore, it was concluded that the interpretation procedure offers a good basis by which to assess whether the measured tensile work reflects a cohesive failure of the gel or a true interaction of the gel with the mucus layer. PMID:11804389

  14. Polymer gel dosimetry of an electron beam in the presence of a magnetic field

    Science.gov (United States)

    Vandecasteele, J.; De Deene, Y.

    2013-06-01

    The effect of a strong external magnetic field on 4 MeV electron beam was measured with polymer gel dosimetry. The measured entrance dose distribution was compared with a calculated fluence map. The magnetic field was created by use of two permanent Neodymium (NdFeB) magnets that were positioned perpendicular to the electron beam. The magnetic field between the magnets was measured with Hall sensors. Based on the magnetic field measurement and the law of Biot-Savart, the magnetic field distribution was extrapolated. Electron trajectories were calculated using a relativistic Lorentz force operator. Although the simplified computational model that was applied, the shape and position of the calculated entrance fluence map are found to be in good agreement with the measured dose distribution in the first layer of the phantom. In combination with the development of low density polymer gel dosimeters, these preliminary results show the potential of 3D gel dosimetry in MRI-linac applications.

  15. Novel composition of polymer gel dosimeters based on N-(Hydroxymethyl)acrylamide for radiation therapy

    Science.gov (United States)

    Basfar, Ahmed A.; Moftah, Belal; Rabaeh, Khalid A.; Almousa, Akram A.

    2015-07-01

    A new composition of polymer gel dosimeters is developed based on radiation induced polymerization of N-(Hydroxymethyl)acrylamide (NHMA) for radiotherapy treatment planning. The dosimeters were irradiated by 10 MV photon beam of a medical linear accelerator at a constant dose rate of 600 cGy/min with doses up to 20 Gy. The polymerization occurs and increases with increasing absorbed dose. The dose response of polymer gel dosimeters was studied using nuclear magnetic imaging (NMR) for relaxation rate (R2) of water proton. Dose rate, energy of radiation and the stability of the polymerization after irradiation were investigated. No appreciable effects of these parameters on the performance of the novel gel dosimeters were observed.

  16. Alginate-Chitosan Microcapsules for Renal Arterial Embolization

    Institute of Scientific and Technical Information of China (English)

    LI Sha; HOU Xin-pu

    2003-01-01

    @@ Two natural, nontoxic, biodegradable and well biocompatible polyelectrolyte polymers, sodium alginate (Alg) and chitosan (CTS), which contain opposite charges, were selected to establish alginate-chitosan microcapsules by electrostatic interaction.

  17. On the mechanical characterization and modeling of polymer gel brain substitute under dynamic rotational loading.

    Science.gov (United States)

    Fontenier, B; Hault-Dubrulle, A; Drazetic, P; Fontaine, C; Naceur, H

    2016-10-01

    The use of highly sensitive soft materials has become increasingly apparent in the last few years in numerous industrial fields, due to their viscous and damping nature. Unfortunately these materials remain difficult to characterize using conventional techniques, mainly because of the very low internal forces supported by these materials especially under high strain-rates of deformation. The aim of this work is to investigate the dynamic response of a polymer gel brain analog material under specific rotational-impact experiments. The selected polymer gel commercially known as Sylgard 527 has been studied using a specific procedure for its experimental characterization and numerical modeling. At first an indentation experiment was conducted at several loading rates to study the strain rate sensitivity of the Sylgard 527 gel. During the unloading several relaxation tests were performed after indentation, to assess the viscous behavior of the material. A specific numerical procedure based on moving least square approximation and response surface method was then performed to determine adequate robust material parameters of the Sylgard 527 gel. A sensitivity analysis was assessed to confirm the robustness of the obtained material parameters. For the validation of the obtained material model, a second experiment was conducted using a dynamic rotational loading apparatus. It consists of a metallic cylindrical cup filled with the polymer gel and subjected to an eccentric transient rotational impact. Complete kinematics of the cup and the large strains induced in the Sylgard 527 gel, have been recorded at several patterns by means of optical measurement. The whole apparatus was modeled by the Finite Element Method using explicit dynamic time integration available within Ls-dyna(®) software. Comparison between the physical and the numerical models of the Sylgard 527 gel behavior under rotational choc shows excellent agreements.

  18. Preparation and characterisation of mucoadhesive nasal gel of venlafaxine hydrochloride for treatment of anxiety disorders

    Directory of Open Access Journals (Sweden)

    Shyamoshree Basu

    2012-01-01

    Full Text Available The aim of the present study is to prepare and evaluate mucoadhesive nasal gels of venlafaxine hydrochloride. Mucoadhesive nasal gels were prepared using polymers like carbopol 934 and sodium alginate and characterized in terms of viscosity, texture profile analysis, ex vivo drug permeation profiles and histopathological studies. The results show that values of viscosity, hardness and adhesiveness increase while those of cohesiveness decrease with corresponding increase in concentration of the polymers. Ex vivo drug permeation profiles showed that formulation containing 5% sodium alginate provided a better controlled release of the drug than the other formulations over a period of 12 h. Histopathological studies assured that gels containing different polymers did not produce any significant change in the nasal mucosae of goat even after 12 h permeation study. Mucoadhesive nasal gel of venlafaxine hydrochloride is a novel dosage form which delivers the drug directly into systemic circulation and provides controlled release of the drug.

  19. In-phantom dosimetry for BNCT with Fricke and normoxic-polymer gels

    Science.gov (United States)

    Gambarini, G.; Agosteo, S.; Carrara, M.; Gay, S.; Mariani, M.; Pirola, L.; Vanossi, E.

    2006-05-01

    Measurements of in-phantom dose distributions and images are important for Boron Neutron Capture Therapy treatment planning. The method for spatial determination of absorbed doses in thermal or epithermal neutron fields, based on Fricke-xylenol-orange-infused gel dosimeters in form of layers, has revealed to be very reliable, as gel layer dosimeters give the possibility of obtaining spatial dose distributions and measurements of each dose contribution in neutron fields, by means of a properly studied procedure. Quite recently, BNCT has been applied to treat liver metastases; in this work the results of in-phantom dosimetry for explanted liver in BNCT treatments are described. Moreover, polyacrylamide gel (PAG) dosimeters in which a polymerization process appears as a consequence of absorbed dose, have been recently tested, because of their characteristic absence of diffusion. In fact, due to the diffusion of ferric ions, Fricke-gel dosimeters require prompt analysis after exposure to avoid spatial information loss. In this work the preliminary results of a study about the reliability of polymer gel in BNCT dosimetry are also discussed. Gel layers have been irradiated in a phantom exposed in the thermal column of the TRIGA MARK II reactor (Pavia). The results obtained with the two kinds of gel dosimeter have been compared.

  20. Photon and neutron kerma coefficients for polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    El-Khayatt, A.M., E-mail: Ahmed_el_khayatt@yahoo.com [Physics Department, College of Science, Al Imam Mohammad Ibn Saud Islamic University (IMSIU) (Saudi Arabia); Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, 13759 Cairo (Egypt); Vega-Carrillo, Hector Rene [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Peñuela, 98068 Zacatecas, Zac. (Mexico)

    2015-08-21

    Neutron and gamma ray kerma coefficients were calculated for 17 3D dosimeters, for the neutron and gamma ray energy ranges extend from 2.53×10{sup −8} to 29 MeV and from 1.0×10{sup −3} to 20 MeV, respectively. The calculated kermas given here for discrete energies and the kerma coefficients are referred to as “point-wise data”. Curves of gamma ray kermas showed slight dips at about 60 keV for most 3D dosimeters. Also, a noticeable departure between thermal and epithermal neutrons kerma sets for water and polymers has been observed. Finally, the obtained results could be useful for dose estimation in the studied 3D dosimeters. - Highlights: • Neutron and gamma ray kerma coefficients were calculated in 17 3D dosimeters. • Curves of gamma-ray kermas showed slight dips at about 60 keV. • Disagreement between neutron kermas for water and polymers has been observed. • The obtained results could be useful for dose estimation in the studied dosimeters.

  1. Correlation between ionic conductivity and fluidity of polymer gel electrolytes containing NH4CF3SO3

    Indian Academy of Sciences (India)

    Harinder Pal Singh; Rajiv Kumar; S S Sekhon

    2005-08-01

    Nonaqueous polymer gel electrolytes containing ammonium triflate (NH4CF3SO3) and dimethylacetamide (DMA) with polymethylmethacrylate (PMMA) as the gelling polymer have been synthesized which show high value of conductivity (∼ 10-2 S/cm) at 25°C. The conductivity of polymer gel electrolytes containing different concentrations of NH4CF3SO3 shows a small decrease with the addition of PMMA and this has been correlated with the variation of fluidity of these gel electrolytes. The small decrease in conductivity with PMMA addition shows that polymer plays the role of stiffener and this is supported by FTIR results which also indicates the absence of any active interaction between polymer and NH4CF3SO3 in these gel electrolytes.

  2. Autonomous Oscillation of Nonthermoresponsive Polymers and Gels Induced by the Belousov–Zhabotinsky Reaction

    Directory of Open Access Journals (Sweden)

    Yusuke Hara

    2013-09-01

    Full Text Available This review introduces the self-oscillating behavior of two types of nonthermoresponsive polymer systems with Ru catalyst moieties for the Belousov-Zhabotinsky (BZ reaction: one with a poly-vinylpyrrolidone (PVP main chain, and the other with a poly(2-propenamide (polyacrylamide (PAM main chain. The amplitude of the VP-based self-oscillating polymer chain and the activation energy for self-oscillation are hardly affected by the initial concentrations of the BZ substrates. The influences of the initial concentrations of the BZ substrates and the temperature on the period of the swelling-deswelling self-oscillation are examined in detail. Logarithmic plots of the period against the initial concentration of one BZ substrate, when the concentrations of the other two BZ substrates are fixed, show good linear relationships. The period of the swelling-deswelling self-oscillation decreases with increasing temperature, in accordance with the Arrhenius equation. The maximum frequency (0.5 Hz of the poly(VP-co-Ru(bpy3 gel is 20 times that of the poly(NIPAAm-co-Ru(bpy3 gel. It is also demonstrated that the amplitude of the volume self-oscillation for the gel has a tradeoff with the self-oscillation period. In addition, this review reports the self-oscillating behavior of an AM-based self-oscillating polymer chain as compared to that of the VP-based polymer chain.

  3. Highly compliant shape memory polymer gels for tunable damping and reversible adhesion

    Science.gov (United States)

    Mrozek, Randy A.; Berg, Michael C.; Gold, Christopher S.; Leighliter, Brad; Morton, Jeffrey T.; Lenhart, Joseph L.

    2016-02-01

    Materials that can dynamically change their properties to better adapt to the local environment have potential utility in robotics, aerospace, and coatings. For some of these applications, most notably robotics, it is advantageous for these responsive materials to be highly compliant in an effort to provide dynamic changes in adhesion and mechanical damping within a broad temperature operational environment. In this report, non-aqueous, highly compliant shape-memory polymer gels are developed by incorporating a low density of chemical cross-links into a physically cross-linked thermoplastic elastomer gel. Chemical cross-linkers were evaluated by varying there size and degree of functionality to determine the impact on the mechanical and adhesive properties. As a result of the chemical cross-linking, the gels exhibit modulus plateaus around room temperature and at elevated temperatures above 100 °C, where the thermoplastic elastomer gel typically melts. The materials were designed so that moduli in the plateaued regions were above and below the Dahlquist criteria of 4 × 104 Pa, respectively, where materials with a modulus below this value typically exhibit an increase in adhesion. The shape memory polymer gels were also integrated into fiber-reinforced composites to determine the temperature-dependent changes in mechanical damping. It is anticipated that this work will provide insight into materials design to provide dynamic changes in adhesion and damping to improve robotic appendage manipulation and platform mobility.

  4. Effect of pH grade on polymer-gel dosimeter and its brachytherapy application

    International Nuclear Information System (INIS)

    To evaluate impact of pH grade on characteristics of polymer-gel dosimeter and its application in dose distribution verification in brachytherapy. A polymer-gel dosimeter based on radiation induced polymerization and crosslinking of acrylic monomers (acrylic acid, N,N' methylen-bis-acrylamide) was investigated with respect to its pH grade. pH grade of a dosimeter was varied by concentration of natrium hydroxide. Afterwards, dosimeter was split into several samples which were uniformly irradiated with Co-60 gamma rays. The range of doses applied was usually from 0 to 50 Gy with the main interest in region up to 20 Gy. Evaluation of dosimeter dose response was performed using MRI (T2). Dose response curves obtained were evaluated with respect to pH grade as a parameter. In parallel, there was studied temperature resistance (melting temperature) of gels with various pH grade. pH grade modified polymer-gel dosimeter was then used to compare dose distribution calculated with brachytherapy treatment planning system for simple irradiation geometry with Ir-192 HDR source. Additionaly, Monte Carlo calculated data were also included in the brachytherapy study. There was observed effect of pH grade on dose-response curve parameters (slope of linear fit, background response, linear range and maximum measurable dose). In general, the lower pH grade the higher sensitivity. Another positive effect of decreased pH grade is significantly higher maximum measurable dose. Maximum melting temperature of a gel was observed with pH grade between 3.5 and 4. For both higher and lower pH grades the melting temperature was lower. Using pH modified polymer-gel dosimeter simple brachytherapy dose distribution was measured and compared with calculated and Monte Carlo simulated data. There was observed strong dependence of dose-response relationship on pH grade of polymer-gel dosimeter resulting in significant improvement of dosimeter characteristics, namely sensitivity, applicable range of

  5. Study on the Ion Association in PVdF-based Gel Polymer Electrolyte

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Gel polymer electrolytes based on the poly (vinylidene fluoride) (PVdF) and the electrolyte of LiClO4 in propylene carbonate (PC) were prepared by the solution casting technique. The ionic conductivity of the gel electrolytes was concentration of lithium salt. Because of the strong coulombiq attractions, the dissolved salt ions might aggregate into ion pairs and multiple ion aggregates. The analysis of DSC and X-ray diffraction revealed that the ions association occurred at higher concentration of lithium salt.

  6. Preparation of a Star Network PEG-based Gel Polymer Electrolyte and Its Application to Electrochromic Devices

    Institute of Scientific and Technical Information of China (English)

    GONG Yong-Feng; FU Xiang-Kai; ZHANG Shu-Peng; JIANG Qing-Long

    2007-01-01

    A star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized,and its corresponding gel polymer electrolyte based on lithium perchlorate and plasticizers EC/PC with the character being colorless and highly transparent has been also prepared. The polymer host was characterized and confirmed to be of a star network and an amorphous structure by FTIR, 1H NMR and XRD studies. The polymer host hold good mechanical properties for pentaerythritol cross-linking. Maximum ionic conductivity of the prepared electrolyte showed that the thermal stability was up to at least 150 ℃. The gel polymer electrolyte was further evaluated in electrochromic devices fabricated by transparent PET-ITO and electrochromically active viologen derivative films, and its excellent performance promised the usage of the gel polymer electrolyte as ionic conductor material in electrochrornic devices.

  7. Characterization of new polyacrylonitrile-co-bis[2-(2-methoxyethoxy)ethyl]itaconate based gel polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Choi, B.K.; Kim, Y.W. [Dankook Univ., Seoul (Korea). Dept. of Applied Physics; Gong, M.S. [Dankook Univ., Seoul (Korea). Dept. of Chemistry; Ahn, S.H. [Battery Research Center, LG Chemical Ltd., Taejon (Korea)

    2001-07-01

    Since the gel polymer electrolytes based on polyacrylonitrile (PAN) host have not been sufficient to fulfil the requirements as a separator of current lithium polymer battery, a new polymer host copolymerized with PAN, polyacrylonitrile-co-bis[2-(2-methoxyethoxy)ethyl]itaconate (abbreviated as PANI), was synthesized in expectation of enhanced trapping ability of liquid electrolytes. Electrical, electrochemical, thermal and mechanical studies have been carried out on PAN and PANI blended gel polymer electrolytes, complexed with ethylene carbonate (EC) and {sup g}amma{sup -}butyrolactone (BL) containing LiClO{sub 4} salt. The addition of PANI as a host polymer in the PAN-based gel polymer electrolytes has beneficial effects such as higher ionic conductivity, better thermal and electrochemical stabilities and enhanced ability of trapping organic solvent, possibly due to ion chelating ability of itaconate unit, though it shows less mechanical rigidity caused by amorphization of the PAN matrix. (Author).

  8. Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

    Science.gov (United States)

    Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Furuta, T.; Fukasaku, K.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2015-02-01

    We study the radiological characteristics of VIP polymer gel dosimeters under carbon beam irradiation with energy of 135 and 290 AMeV. To evaluate dose response of VIP polymer gels, the transverse (or spin-spin) relaxation rate R2 of the dosimeters measured by magnetic resonance imaging (MRI) as a function of linear energy transfer (LET), rather than penetration depth, as is usually done in previous reports. LET is evaluated by use of the particle transport simulation code PHITS. Our results reveal that the dose response decreases with increasing dose-averaged LET and that the dose response-LET relation also varies with incident carbon beam energy. The latter can be explained by taking into account the contribution from fragmentation products.

  9. Studies of plastic crystal gel polymer electrolytes based on poly(vinylidene chloride-co-acrylonitrile)

    Science.gov (United States)

    Hambali, D.; Zainuddin, Z.; Supa'at, I.; Osman, Z.

    2016-02-01

    In this work, we have prepared systems of poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) based gel polymer electrolytes (GPEs) which are single plasticized-GPEs and double plasticized-GPEs. Both systems comprised plastic crystal succinonitrile SN to form plastic crystal gel polymer electrolyte (PGPE) films. The ionic conductivity of the PGPE films were analysed by means of a.c. impedance spectroscopy at room temperature as well as at the temperature range of 303 K to 353 K. The temperature dependence ionic conductivity was found to obey the VTF rule. To study the interactions among the constituents in the PGPEs, Fourier Transform Infrared Spectroscopy (FTIR) was carried out and hence, the complexation between them has also been confirmed.

  10. Contrast enhancement of magnetic resonance imaging (MRI) of polymer gel dosimeter by adding Platinum nano- particles

    International Nuclear Information System (INIS)

    In this research different concentrations of Platinum nanoparticles (Pt-NPs) embedded in PAGAT polymer gel and irradiated with Cobalt -60 (60Co). The OD of samples indicate significant dose enhancement caused by Pt-NPs. Different concentrations of Pt-NPs were investigated: 0.5×10−2,1×10−2 2×10−2 and 3×10−2 mg/l and these were presented the enhancement in OD by the factor of 11.56, 27.10, 15.84 and 10.07 respectively. As the mean energy of 60Co is 1.25 MeV and atomic number (Z) of Pt is 78, the predominant effect will be Compton effect and Photoelectric cannot occurred. This work studied the feasibility of using PAGAT polymer gel combined with Pt-NPs as a suitable tool to perform dosimetric investigation of nanoparticles application in radiotherapy as dosimeter and dose enhancer

  11. Effect of the exothermal polymerization reaction on polymer gel dosimetric measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sedaghat, Mahbod; Bujold, Rachel; Lepage, Martin, E-mail: mahbod.sedaghat@Usherbrooke.c

    2010-11-01

    Discrepancies in polymer gel dosimetric measurements have been observed between containers of different sizes receiving the same radiation dose. We hypothesized that these deviations are caused by a change in the rate of polymerization due to internal heat increase in the gel containers resulting from the exothermic polymerization of monomers. Here, we test this hypothesis in a polyacrylamide gel dosimeter by recording the temperature in glass phantoms of different sizes during and after irradiation. The dose response of the samples was determined with magnetic resonance imaging. The difference of R{sub 2} values along the depth of the containers was below {+-}1%. We discuss that this small difference can be attributed to variations in the rate of gelatin cooling during manufacture rather than to the measured heat increase during irradiation.

  12. An x-ray CT polymer gel dosimetry prototype: I. Remnant artefact removal.

    Science.gov (United States)

    Jirasek, A; Carrick, J; Hilts, M

    2012-05-21

    In this study a new x-ray CT polymer gel dosimetry (PGD) filtering technique is presented for the removal of (i) remnant ring and streak artefacts, and (ii) 'structured' noise in the form of minute, intrinsic gel density fluctuations. It is shown that the noise present within x-ray CT PGD images is not purely stochastic (pixel by pixel) in nature, but rather is 'structured', and hence purely stochastic-based noise-removal filters fail in removing this significant, unwanted noise component. The remnant artefact removal (RAR) technique is based on a class of signal stripping (i.e. baseline-estimation) algorithms typically used in the estimation of unwanted non-uniform baselines underlying spectral data. Here the traditional signal removal algorithm is recast, whereby the 'signal' that is removed is the structured noise and remnant artefacts, leaving the desired polymer gel dose distribution. The algorithm is extended to 2D and input parameters are optimized for PGD images. RAR filter results are tested on (i) synthetic images with measured gel background images added, in order to accurately represent actual noise present in PGD images, and (ii) PGD images of a three-field gel irradiation. RAR results are compared to a top-performing noise filter (adaptive mean, AM), used in previous x-ray CT PGD studies. It is shown that, in all cases, the RAR filter outperforms the AM filter, particularly in cases where either (i) a low-dose gel image has been acquired or (ii) the signal-to-noise ratio of the PG image is low, as in the case when a low number of image averages are acquired within a given experiment. Guidelines for the implementation of the RAR filter are given.

  13. Tubular array, dielectric, conductivity and electrochemical properties of biodegradable gel polymer electrolyte

    International Nuclear Information System (INIS)

    Highlights: • A new finding of tubular array of 10–20 μm in length and 1–2 μm in thickness of gel polymer electrolyte (GPE) having 2.2 × 10−3 S cm−1 conductivity is reported. • Thermal and electrochemical characterizations of GPEs show good interaction among the polymer, plasticizer and salt. • GPE based supercapacitor demonstrates high capacitance of 186 F g−1. • Low temperature studies did not influence much on capacitance values obtained from AC impedance studies. • Charge–discharge exhibits high capacity with excellent cyclic stability and energy density. -- Abstract: A supercapacitor based on a biodegradable gel polymer electrolyte (GPE) has been fabricated using guar gum (GG) as the polymer matrix, LiClO4 as the doping salt and glycerol as the plasticizer. The scanning electron microscopy (SEM) images of the gel polymer showed an unusual tubular array type surface morphology. FTIR, DSC and TGA results of the GPE indicated good interaction between the components used. Highest ionic conductivity and lowest activation energy values were 2.2 × 10−3 S cm−1 and 0.18 eV, respectively. Dielectric studies revealed ionic behavior and good capacitance with varying frequency of the GPE system. The fabricated supercapacitor showed a maximum specific capacitance value of 186 F g−1 using cyclic voltammetry. Variation of temperature from 273 K to 293 K did not significantly influence the capacitance values obtained from AC impedance studies. Galvanostatic charge–discharge study of supercapacitor indicated that the device has good stability, high energy density and power density

  14. Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios

    Energy Technology Data Exchange (ETDEWEB)

    G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Feiyan Chen

    2005-12-31

    Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of a 42-month research program that focused on the understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work was conducted on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A rate equation that describes the reaction between chromium acetate and polymer molecules was regressed from experimental data. A mathematical model that describes the crosslinking reaction between two polymer molecules as a function of time was derived. The model was based on probability concepts and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. Average molecular weights of pre-gel aggregates were measured as a function of time and were comparable to model simulations. Experimental methods to determine molecular weight distributions of pre-gel aggregates were unsuccessful. Dissolution of carbonate minerals during the injection of gelants causes the pH of the gelant to increase. Chromium precipitates from solution at the higher pH values robbing the gelant of crosslinker. Experimental data on the transport of chromium acetate solutions through dolomite cores were obtained. A mathematical model that describes the transport of brine and chromium acetate solutions through rocks containing carbonate minerals was used to simulate the experimental results and data from literature. Gel treatments usually reduce the permeability

  15. Effect of polymer aggregation on the open circuit voltage in organic photovoltaic cells: aggregation-induced conjugated polymer gel and its application for preventing open circuit voltage drop.

    Science.gov (United States)

    Kim, Bong-Gi; Jeong, Eun Jeong; Park, Hui Joon; Bilby, David; Guo, L Jay; Kim, Jinsang

    2011-03-01

    To investigate the structure-dependent aggregation behavior of conjugated polymers and the effect of aggregation on the device performance of conjugated polymer photovoltaic cells, new conjugated polymers (PVTT and CN-PVTT) having the same regioregularity but different intermolecular packing were prepared and characterized by means of UV-vis spectroscopy and atomic force microscopy (AFM). Photovoltaic devices were prepared with these polymers under different polymer-aggregate conditions. Polymer aggregation induced by thermal annealing increases the short circuit current but provides no advantage in the overall power conversion efficiency because of a decrease in the open circuit voltage. The device fabricated from a pre-aggregated polymer suspension, acquired from ultrasonic agitation of a conjugated polymer gel, showed enhanced performance because of better phase separation and reduced recombination between polymer/PCBM.

  16. 纤维蛋白凝胶包裹的万古霉素藻酸盐微球的制备与优选%Preparation and optimization of fibrin-gel-coated vancomycin alginate beads

    Institute of Scientific and Technical Information of China (English)

    侯天勇; 吴雪晖; 许建中; 李强; 冯江华

    2008-01-01

    目的 制备和优化纤维蛋白凝胶包裹的万古霉素藻酸盐微球(fibrin-gel-coated vancomycin alginate beads,FG-Vanco-AB),探讨其在骨科抗感染治疗中的可能应用.方法 应用滴注法制备万古霉素藻酸盐微球,通过分别改变万古霉素和藻酸盐溶液的浓度,优选万古霉素含量高的微球;然后用不同浓度纤维蛋白凝胶包裹,通过检测各组万古霉素有效的释放时间来筛选适当包裹微球.结果 随着万占霉素和藻酸盐溶液浓度的升高,微球中的万占霉素含量增高,16%藻酸盐和50 mg/ml万古霉素等体积混合液制备的微球中万古霉素含量最高,达(27.36±0.90)%;在前述微球的基础上,用不同浓度纤维蛋白包裹的微球的缓释实验显示,75 ms/ml纤维蛋白包裹的微球释放的万占霉素的浓度达到可有效杀灭金黄色葡萄球菌的天数为19 d.结论 优选后的FGVanco-AB可达到有效杀菌浓度的释放天数显著延长,增加了临床应用的可能性.%Objective To prepare and optimize fibrin-gel-coated vaneomycin alginate beads (FG-Vanco-AB)and investigate their possible use in treatment of osteomyelitis or prevention of infection.Methods Vancomycin alginate beads were produced by dropping vancomycin and alginate mixed liquor into calcium chloride solution.Beads including high vancomycin content were prepared and chosen by optimizing different concentrations of vancomycin solution and alginate solution.These beads were coated with fibrin gel formed by different concentrations of fibrin and the same concentration thrombin.The optimized beads were selected based on available release time,when vancomycin in medium could kill Staphylococcus aureus(ATCC25923). Results Higher content of vancomycin in bead resulted in increase of vancomycin concentration and alginate concentration in mixed liquid.The highest vancomycin content beads were prepared by 16%alginate and 50 mr/ml vancomycin,up to(27.36±0.90)%.The further results showed

  17. Deformation of redox-active polymer gel based on polysiloxane backbone and bis(benzodithiolyl)bithienyl scaffold.

    Science.gov (United States)

    Ohtake, Toshihiro; Tanaka, Hideki; Matsumoto, Tetsuro; Ohta, Akira; Kimura, Mutsumi

    2014-12-01

    Redox-active polymer gels consisting of polysiloxane backbone and bis(benzodithiolyl)bithienyl units have been designed and synthesized. The bis(benzodithiolyl)bithienyl units, which undergo interconversion between cyclic form and opened dicationic form, have been incorporated into polysiloxane backbone via hydrosilylation of vinyl-terminated bis(benzodithiolyl)bithienyl derivative and poly(methylhydrosiloxane) (PMHS) or poly(dimethylsiloxane-co-hydrogenmethylsiloxane) (PDMS-co-PMHS), resulting in polymer gels cross-linked with bis(benzodithiolyl)bithienyl units. After the incorporation of M1 into polysiloxane backbone, these polymer gels (P1 and P2) also exhibit redox responses associated with the electrochemical interconversion of the bis(benzodithiolyl)bithienyl moieties. The polymer gels show swelling behavior upon chemical oxidization, and bending behavior has been observed for the polymer gel immobilized poly(vinylidene difluoride) (PVdF) film. These results provide a useful perspective for fabricating redox-triggered polymer gel actuators based on the conformational change of the functional molecular unit. PMID:25400032

  18. FORMULATION AND EVALUATION OF FLOATING IN SITU GEL BASED GASTRO RETENTIVE DRUG DELIVERY OF CIMETIDINE

    Directory of Open Access Journals (Sweden)

    Bhargav D. Jayswal

    2012-05-01

    Full Text Available The present investigation deals with the formulation and evaluation of sodium alginate and pectin basedIn situ gel of Cimetidine. Sodium alginate and pectin were used as a polymer and CaCO3 was used as across-linking agent. In-situ forming polymeric formulations drug delivery systems is in sol form beforeadministration in the body, but once administered, undergoes gelation in-situ to form a gel. Theformulation of gel depends upon factors like temperature modulation, pH changes, presence of ions andultra-violet irradiation, from which drug gets released in sustained and controlled manner. The objectiveof this study was to develop a novel in- situ gel system for sustained drug delivery using naturalbiodegradable polymers. The system utilizes polymers that exhibit sol-to-gel phase transition due tochange in specific physico-chemical parameters. In-situ gel was formed at a biological pH. In vitrorelease studies were conducted in simulated gastric fluid and cumulative amount of drug release wasanalyzed by spectrophotometry. From designed set of experiments, it was evident that formulationcontaining 1.2% of sodium alginate and 1.5% of pectin control the release of drug for longer duration.The in-situ gel exhibited the expected, viscosity, drug content, pH, in vitro gelling capacity, in vitrofloating ability, water uptake ability and sustained drug release.The drug release from the in situ gelsfollows the fickian diffusion type of release.

  19. The application of polymer gel dosimeters to dosimetry for targeted radionuclide therapy

    International Nuclear Information System (INIS)

    There is a lack of standardized methodology to perform dose calculations for targeted radionuclide therapy and at present no method exists to objectively evaluate the various approaches employed. The aim of the work described here was to investigate the practicality and accuracy of calibrating polymer gel dosimeters such that dose measurements resulting from complex activity distributions can be verified. Twelve vials of the polymer gel dosimeter, 'MAGIC', were uniformly mixed with varying concentrations of P-32 such that absorbed doses ranged from 0 to 30 Gy after a period of 360 h before being imaged on a magnetic resonance scanner. In addition, nine vials were prepared and irradiated using an external 6 MV x-ray beam. Magnetic resonance transverse relaxation time, T2, maps were obtained using a multi-echo spin echo sequence and converted to R2 maps (where T2 = 1/R2). Absorbed doses for P-32 irradiated gel were calculated according to the medical internal radiation dose schema using EGSnrc Monte Carlo simulations. Here the energy deposited in cylinders representing the irradiated vials was scored. A relationship between dose and R2 was determined. Effects from oxygen contamination were present in the internally irradiated vials. An increase in O2 sensitivity over those gels irradiated externally was thought to be a result of the longer irradiation period. However, below the region of contamination dose response appeared homogenous. Due do a drop-off of dose at the periphery of the internally irradiated vials, magnetic resonance ringing artefacts were observed. The ringing did not greatly affect the accuracy of calibration, which was comparable for both methods. The largest errors in calculated dose originated from the initial activity measurements, and were approximately 10%. Measured R2 values ranged from 5-35 s-1 with an average standard deviation of 1%. A clear relationship between R2 and dose was observed, with up to 40% increased sensitivity for internally

  20. The application of polymer gel dosimeters to dosimetry for targeted radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gear, J I [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Flux, G D [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Charles-Edwards, E [Clinical Magnetic Research Group, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Partridge, M [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Cook, G [Department of Nuclear Medicine, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom); Ott, R J [Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey (United Kingdom)

    2006-07-21

    There is a lack of standardized methodology to perform dose calculations for targeted radionuclide therapy and at present no method exists to objectively evaluate the various approaches employed. The aim of the work described here was to investigate the practicality and accuracy of calibrating polymer gel dosimeters such that dose measurements resulting from complex activity distributions can be verified. Twelve vials of the polymer gel dosimeter, 'MAGIC', were uniformly mixed with varying concentrations of P-32 such that absorbed doses ranged from 0 to 30 Gy after a period of 360 h before being imaged on a magnetic resonance scanner. In addition, nine vials were prepared and irradiated using an external 6 MV x-ray beam. Magnetic resonance transverse relaxation time, T{sub 2}, maps were obtained using a multi-echo spin echo sequence and converted to R{sub 2} maps (where T{sub 2} = 1/R{sub 2}). Absorbed doses for P-32 irradiated gel were calculated according to the medical internal radiation dose schema using EGSnrc Monte Carlo simulations. Here the energy deposited in cylinders representing the irradiated vials was scored. A relationship between dose and R{sub 2} was determined. Effects from oxygen contamination were present in the internally irradiated vials. An increase in O{sub 2} sensitivity over those gels irradiated externally was thought to be a result of the longer irradiation period. However, below the region of contamination dose response appeared homogenous. Due do a drop-off of dose at the periphery of the internally irradiated vials, magnetic resonance ringing artefacts were observed. The ringing did not greatly affect the accuracy of calibration, which was comparable for both methods. The largest errors in calculated dose originated from the initial activity measurements, and were approximately 10%. Measured R{sub 2} values ranged from 5-35 s{sup -1} with an average standard deviation of 1%. A clear relationship between R{sub 2} and dose was

  1. Modeling the controllable pH-responsive swelling and pore size of networked alginate based biomaterials.

    Science.gov (United States)

    Chan, Ariel W; Neufeld, Ronald J

    2009-10-01

    Semisynthetic network alginate polymer (SNAP), synthesized by acetalization of linear alginate with di-aldehyde, is a pH-responsive tetrafunctionally linked 3D gel network, and has potential application in oral delivery of protein therapeutics and active biologicals, and as tissue bioscaffold for regenerative medicine. A constitutive polyelectrolyte gel model based on non-Gaussian polymer elasticity, Flory-Huggins liquid lattice theory, and non-ideal Donnan membrane equilibria was derived, to describe SNAP gel swelling in dilute and ionic solutions containing uni-univalent, uni-bivalent, bi-univalent or bi-bi-valent electrolyte solutions. Flory-Huggins interaction parameters as a function of ionic strength and characteristic ratio of alginates of various molecular weights were determined experimentally to numerically predict SNAP hydrogel swelling. SNAP hydrogel swells pronouncedly to 1000 times in dilute solution, compared to its compact polymer volume, while behaving as a neutral polymer with limited swelling in high ionic strength or low pH solutions. The derived model accurately describes the pH-responsive swelling of SNAP hydrogel in acid and alkaline solutions of wide range of ionic strength. The pore sizes of the synthesized SNAP hydrogels of various crosslink densities were estimated from the derived model to be in the range of 30-450 nm which were comparable to that measured by thermoporometry, and diffusion of bovine serum albumin. The derived equilibrium swelling model can characterize hydrogel structure such as molecular weight between crosslinks and crosslinking density, or can be used as predictive model for swelling, pore size and mechanical properties if gel structural information is known, and can potentially be applied to other point-link network polyelectrolytes such as hyaluronic acid gel. PMID:19660810

  2. Novel Alginate Microcapsules for Cell Therapy – A study of the structure-function relationships in native and structurally engineered alginates

    OpenAIRE

    Mørch, Yrr A.

    2008-01-01

    Alginate microcapsules have the potential as immune barriers for cell transplantation where the alginate gel protects the transplant from the host immune system. Microencapsulation can thus provide a way to overcome the need for immunosuppressive drugs. The successful use of alginates as immobilization material has, however, been hampered by their mechanical instability and high porosity. To overcome this problem, a polycation layer has traditionally been added to the alginate gels. However, ...

  3. Thermostable gel polymer electrolyte based on succinonitrile and ionic liquid for high-performance solid-state supercapacitors

    Science.gov (United States)

    Pandey, Gaind P.; Liu, Tao; Hancock, Cody; Li, Yonghui; Sun, Xiuzhi Susan; Li, Jun

    2016-10-01

    A flexible, free-standing, thermostable gel polymer electrolyte based on plastic crystalline succinonitrile (SN) and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) entrapped in copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) is prepared and optimized for application in solvent-free solid-state supercapacitors. The synthesized gel polymer electrolyte exhibits a high ionic conductivity over a wide temperature range (from ∼5 × 10-4 S cm-1 at -30 °C up to ∼1.5 × 10-2 S cm-1 at 80 °C) with good electrochemical stability window (-2.9 to 2.5 V). Thermal studies confirm that the SN containing gel polymer electrolyte remains stable in the same gel phase over a wide temperature range from -30 to 90 °C. The electric double layer capacitors (EDLCs) have been fabricated using activated carbon as active materials and new gel polymer electrolytes. Electrochemical performance of the EDLCs is assessed through cyclic voltammetry, galvanostatic charge-discharge cycling and impedance spectroscopy. The EDLC cells with the proper SN-containing gel polymer electrolyte has been found to give high specific capacitance 176 F g-1 at 0.18 A g-1 and 138 F g-1 at 8 A g-1. These solid-state EDLC cells show good cycling stability and the capability to retain ∼80% of the initial capacitance after 10,000 cycles.

  4. Structure and Hydrogen Bonding of Water in Polyacrylate Gels: Effects of Polymer Hydrophilicity and Water Concentration.

    Science.gov (United States)

    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. PMID:26514915

  5. 凝胶聚合物电解质的研究进展%Research Progress of Gel Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    万玉荣; 乔庆东; 李琪

    2015-01-01

    Several kinds of polymer materials used as the matrix of gel polymer electrolytes were introduced, such as polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), poly (vinylidene fluoride) (PVDF). Currently, research on gel polymer electrolyte is still in the primary stage. And there are many problems in the study of gel polymer electrolytes. In this article, modification methods of gel polymer electrolytes were discussed, such as crosslinking, copolymerization, blending or adding fillers, and so on. The application prospect of gel polymer electrolytes was analyzed.%介绍了几种聚合物高分子材料,常以其作为凝胶聚合物电解质基体。如聚氧化乙烯(PEO)、聚丙烯腈(PAN)、聚甲基丙烯酸甲酯(PMMA)、聚偏氟乙烯(PVDF)。对于凝胶聚合物电解质的研究,目前仍处于初级阶段,还存在许多问题。本文探讨了凝胶聚合物电解质的改性方法,主要有交联、共聚、共混或添加填料等,并展望了凝胶聚合物电解质的应用前景。

  6. Theory of DNA electrophoresis in physical gels and entangled polymer solutions

    Science.gov (United States)

    Duke, Thomas; Viovy, Jean Louis

    1994-03-01

    A scaling theory is presented for the electrophoretic mobility of DNA in sieving media that form dynamically evolving meshworks, such as physical gels and solutions of entangled polymers. In such media, the topological constraints on the DNA's motion are perpetually changing as cross links break and rejoin or as the polymers diffuse. It is shown that if the rate of constraint release falls within a certain range (which depends on the field strength), fractionation can be extended to higher molecular weights than would be feasible using a permanent gel of equivalent pore size. This improvement is a consequence of the disruptive effect that constraint release has on the mechanism of molecular orientation. Numerical simulations support the predictions of the theory. The possibility of realizing such a system in practice, with the aim of improving on current electrophoresis methods, is commented upon. It is suggested that semidilute polymer solutions may be a versatile medium for the rapid separation of long single-stranded DNA molecules, and the particular quality of solution required is identified.

  7. 4.4 V lithium-ion polymer batteries with a chemical stable gel electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Takeru; Hara, Tomitaro; Akashi, Hiroyuki [Sony Corporation, Energy Business Group, R and D Division, 1-1 Aza, Shimosugishita, Takakura, Hiwada-machi, Koriyama-shi, Fukushima 963-0531 (Japan); Segawa, Ken; Honda, Kazuo [Sony Energy Device Corporation, PB Technology Center, 1-1 Aza, Shimosugishita, Takakura, Hiwada-machi, Koriyama-shi, Fukushima 963-0531 (Japan)

    2007-12-06

    We tested 4.2 V Li-ion polymer batteries (LIPB) with physical gel electrolyte, poly(vinylidene fluoride) (PVDF), 4.4 V LIPB and 4.4 V Li-ion batteries (LIB) with a liquid electrolyte. The discharge capacity of the 4.4 V LIPB reached 520 Wh l{sup -1} which was 9% higher than that of the 4.2 V LIPB. The 4.4 V LIPB had a high capacity retention ratio of 91.4% at 3 C because of the excellent ion conductivity of the PVDF gel. The capacity retention ratio of the 4.4 V LIPB was 82% after 500 cycles, which is comparable to those of some commercial LIBs. The 4.4 V LIPB retained its original thickness even after many cycles and after being stored at 90 C, whereas the 4.4 V LIB swelled by over 20%. Peaks in the FT-IR spectrum of the discolored separator in the 4.4 V LIB after storage were assigned to C=C double bonds, suggesting that the separator in direct contact with the 4.4 V cathode had been oxidized. The PVDF gel electrolyte not only had a high ionic conductivity but also completely suppressed oxidation. The 4.4 V LIPB with PVDF gel electrolyte has properties suitable for practical cells, namely, high energy density, high permanence and it is safe to use. (author)

  8. Superspreading on Immersed Gel Surfaces for the Confined Synthesis of Thin Polymer Films.

    Science.gov (United States)

    Zhang, Pengchao; Zhang, Feilong; Zhao, Chuangqi; Wang, Shutao; Liu, Mingjie; Jiang, Lei

    2016-03-01

    Liquid spreading is of significant interest in science and technology. Although surface topography engineering and liquid surface-tension regulating can facilitate spreading, the spreading layers in these strategies are inevitably inhomogeneous or contaminated with surfactants. Herein, we show a general strategy to realize the superspreading of liquids on mutually soluble gel surfaces. The cooperation of the hydraulic pressure under liquid phase and liquid-like property of gel surfaces can dramatically eliminate the local pinning effect and enhance the advancement of three-phase contact line, thus forming stable and homogeneous superspreading liquid layers. Such liquid layers can be converted into various functional thin polymer films with controlled thicknesses (nm- to µm-scale) through one-step polymerization of the reactants. Our strategy offers opportunities for large-scale synthesis of versatile functional thin films for various applications. PMID:26880685

  9. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    Directory of Open Access Journals (Sweden)

    Timothy Olding

    2011-01-01

    Full Text Available This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI. For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low′s gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery. When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low′s gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a from the same gel batch and (b from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.

  10. Nanostructured electrodes and gel-polymer electrolyte for an improved Li-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Bodoardo, S.; Bongiovanni, R.; Gerbaldi, C.; Meligrana, G.; Nair, J. [Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino (Italy); Mulas, G. [Dipartimento di Chimica, Universita di Sassari (Italy); Penazzi, N.

    2009-06-15

    The present communication deals with the results obtained by the electrochemistry research group at the Politecnico di Torino in Italy in the field of materials for Li-ion cells. Cathode (LiFePO{sub 4}/C powder), anode (Ni{sub 3}Sn{sub 4}-C alloy) and electrolyte (gel-polymer membrane) cell components have been prepared with the aim of obtaining, beyond high performance, cheap materials from easily disposable reagents via simple and reliable preparations. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  11. Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y.; Wuu, Cheng-Shie; Maryanski, Marek J. [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States); Department of Radiation Oncology, Columbia University, New York, New York 10032 and MGS Research Inc., Madison, Connecticut 06443 (United States)

    2010-02-15

    The dose response of the BANG 3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurements on the 18 glass vials irradiated with graded doses from 0 to 4 Gy using 6 or 10 MV large field irradiations; (b) optical-CT scanning of Barex cylinders irradiated with graded doses (0.5, 1, 1.5, and 2 Gy) from four adjacent 4x4 cm{sup 2} photon fields or 6x6 cm{sup 2} electron fields; and (c) percent depth dose (PDD) comparison of optical-CT scans with ion chamber measurements for 6x6 cm{sup 2}, 12 and 16 MeV electron fields. The dose response of the BANG 3 gel was found to be linear and energy independent within the uncertainties of the experimental methods (about 3%). The slopes of the linearly fitted dose response curves (dose sensitivities) from the four field irradiations (0.0752{+-}3%, 0.0756{+-}3%, 0.0767{+-}3%, and 0.0759{+-}3% cm{sup -1} Gy{sup -1}) and the PDD matching methods (0.0768{+-}3% and 0.0761{+-}3% cm{sup -1} Gy{sup -1}) agree within 2.2%, indicating a good reproducibility of the gel dose response within phantoms of the same geometry. The dose sensitivities from the glass vial approach are different from those of the cylindrical Barex phantoms by more than 30%, owing probably to the difference in temperature inside the two types of phantoms during gel formation and irradiation, and possible oxygen contamination of the glass vial walls. The dose response curve obtained from the PDD matching approach with 16 MeV electron field was used to calibrate the gel phantom irradiated with the 12 MeV, 6x6 cm{sup 2} electron field. Three-dimensional dose distributions

  12. Characterization of dose-dependent Young's modulus for a radiation-sensitive polymer gel

    International Nuclear Information System (INIS)

    Radiation-sensitive polymer gels for clinical dosimetry have been intensively investigated with magnetic resonance imaging (MRI) because the transversal magnetic relaxation time is dependent on irradiation dose. MRI is expensive and not easily available in most clinics. For this reason, low-cost, quick and easy-to-use potential alternatives such as optical computed tomography (CT), x-ray CT or ultrasound attenuation CT have also been studied by others. Here, we instead evaluate the dose dependence of the elastic material property, Young's modulus and the dose response of the viscous relaxation of radiation-sensitive gels to discuss their potential for dose imaging. Three batches of a radiation-sensitive polymer gel (MAGIC gel) samples were homogeneously irradiated to doses from 0 Gy to 45.5 Gy. Young's modulus was computed from the measured stress on the sample surface and the strain applied to the sample when compressing it axially, and the viscous relaxation was determined from the stress decay under sustained compression. The viscous relaxation was found not to change significantly with dose. However, Young's modulus was dose dependent; it approximately doubled in the gels between 0 Gy and 20 Gy. By fitting a second-order polynomial to the Young's modulus-versus-dose data, 99.4% of the variance in Young's modulus was shown to be associated with the change in dose. The precision of the gel production, irradiation and Young's modulus measurement combined was found to be 4% at 2 Gy and 3% at 20 Gy. Potential sources of measurement error, such as those associated with the boundary conditions in the compression measurement, inhomogeneous polymerization, temperature (up to 1% error) and the evaporation of water from the sample (up to 1% error), were estimated and discussed. It was concluded that Young's modulus could be used for dose determination. Imaging techniques such as elastography may help to achieve this if they can provide a local measurement of Young

  13. Silk sericin loaded alginate nanoparticles: Preparation and anti-inflammatory efficacy.

    Science.gov (United States)

    Khampieng, Thitikan; Aramwit, Pornanong; Supaphol, Pitt

    2015-09-01

    In this study, silk sericin loaded alginate nanoparticles were prepared by the emulsification method followed by internal crosslinking. The effects of various silk sericin loading concentration on particle size, shape, thermal properties, and release characteristics were investigated. The initial silk sericin loadings of 20, 40, and 80% w/w to polymer were incorporated into these alginate nanoparticles. SEM images showed a spherical shape and small particles of about 71.30-89.50 nm. TGA analysis showed that thermal stability slightly increased with increasing silk sericin loadings. FTIR analysis suggested interactions between alginate and silk sericin in the nanoparticles. The release study was performed in acetate buffer at normal skin conditions (pH 5.5; 32 °C). The release profiles of silk sericin exhibited initial rapid release, consequently with sustained release. These silk sericin loaded alginate nanoparticles were further incorporated into topical hydrogel and their anti-inflammatory properties were studied using carrageenan-induced paw edema assay. The current study confirms the hypothesis that the application of silk sericin loaded alginate nanoparticle gel can inhibit inflammation induced by carrageenan. PMID:26188300

  14. Removal of radioactive nuclides by alginate microcapsules

    Energy Technology Data Exchange (ETDEWEB)

    Mimura, H.; Oritani, T.; Akiba, K. [Tohoku Univ., Institute of Multidisciplinary Research for Advanced Materials, Sendai, Miyagi (Japan)

    2002-11-01

    The microcapsules enclosing two kinds of functional materials, inorganic ion-exchangers and organic extractants, were prepared by taking advantage of the high immobilization ability of alginate gel polymer. The K{sub d} values of Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Y{sup 3+}, Eu{sup 3+} and Am{sup 3+}, for a favorable microcapsule (CuFC/clinoptilolite/DEHPA/CaALG) were estimated to be 1.1x10{sup 4}, 7.5x10, 1.1x10, 1.0x10{sup 4}, 1.4x10{sup 4}, 3.4x10{sup 3} cm{sup 3}/g, respectively. The microcapsules with various shapes such as spherical, columnar, fibrous and filmy forms were easily prepared by changing the way of dipping kneaded sol into the gelling salt solutions. The alginate microcapsules have a potential possibility for the simultaneous removal of various radioactive nuclides from waste solutions. (author)

  15. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    Science.gov (United States)

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-08-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering.

  16. Thermo-controlled rheology of electro-assembled polyanionic polysaccharide (alginate) and polycationic thermo-sensitive polymers.

    Science.gov (United States)

    Niang, Pape Momar; Huang, Zhiwei; Dulong, Virginie; Souguir, Zied; Le Cerf, Didier; Picton, Luc

    2016-03-30

    Several thermo-sensitive polyelectrolyte complexes were prepared by ionic self-association between an anionic polysaccharide (alginate) and a monocationic copolymer (polyether amine, Jeffamine®-M2005) with a 'Low Critical Solubility Temperature' (LCST). We show that electro-association must be established below the aggregation temperature of the free Jeffamine®, after which the organization of the system is controlled by the thermo-association of Jeffamine® that was previously electro-associated with the alginate. Evidence for this comes primarily from the rheology in the semi-dilute region. Electro- and thermo-associative behaviours are optimal at a pH corresponding to maximum ionization of both compounds (around pH 7). High ionic strength could prevent the electro-association. The reversibility of the transition is possible only at temperatures lower than the LCST of Jeffamine®. Similar behaviour has been obtained with carboxymethyl cellulose (CMC), which suggests that this behaviour can be observed using a range of anionic polyelectrolytes. In contrast, no specific properties have been found for pullulan, which is a neutral polysaccharide. PMID:26794948

  17. In vitro permeation studies of phenolics from horse chestnut seed gels prepared with different polyacrylic acid polymer derivatives

    Directory of Open Access Journals (Sweden)

    Zelbienė Eglė

    2015-06-01

    Full Text Available The aim of this study was to investigate the effects of polyacrylic acid polymers (Ultrez 10, Ultrez 20, Carbopol 980, and Carbopol 940 on the viscosity and the in vitro permeation of phenolic compounds from the gel prepared from natural horse chestnut seed extract. Experiments were performed in the presence and in the absence of peppermint oil (Mentha piperita. Our results showed that peppermint oil decreased the viscosity of the gels and permeation of phenolic compounds from all gel samples. Results show that the highest content of phenolic compounds (1.758 μg cm-2 permeated in vitro from gel based on Carbopol Ultrez 20 without peppermint oil added (p < 0.05 vs. other tested polymers.

  18. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

    Science.gov (United States)

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

    2016-05-01

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures.

  19. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries.

    Science.gov (United States)

    Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G; Lee, Yoon-Sung; Kim, Dong-Won

    2016-01-01

    Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures. PMID:27189842

  20. Comparative study on the effects of negatively-charged biopolymers on chitosan-based gels for the development of instantaneous gels

    International Nuclear Information System (INIS)

    Polymeric electrolytic complexes are solutions of charged/ionized chains. These solutions of positive and negative charge can be combined to make instantaneous networks bonded by electrostatic interactions, a gel network. These electrostatic interaction allows for easy application in injectable gels as the network can be temporarily distributed with the application of force and reformed on the relief of it. Possible applications for these injectable gels include drug delivery and wound-healing. κ-Carrageenan, dextran sulfate, alginate, and chitosan are polyelectrolytic biocompatible polymers which are widely studied and used for a variety of biomedical applications. Gel networks are made by combining a negatively-charged (κ-Carrageenan, dextran sulfate, or alginate) and positively charged (chitosan) solutions. The strong electrostatic interaction between the opposite charges from the gel network and the inherent biocompatibility of the polymers allow future biomedical applications. Quat 188-modified chitosan has additional sites for electrostatic bonding, can be dissolved in neutral, basic, and acidic pH, and has shown inherent antibacterial activity. The objectives of this study are the following: to formulate chitosan-based gels mixing solutions of chitosan with solutions of either κ-Carrageenan, dextran sulfate, or alginate, study the gelation of the gels as function of time and pH (4, 7, and 9) using UV-Vis, characterize the chitosan-based gels through DSC and DMA, characterize the physiological degradation of the chitosan-based gels, and compare results with those from Quat 188-modified chitosan-based gels. Polyelectrolytic solutions of chitosan and negatively-charged biopolymer of similar viscosities were mixed. It was determined from the UV-Vis spectroscopy of the chitosan-carrageenan gels under pH7 buffer that the increase of concentration by a factor of 5 for 0.006M-0.0095M and 1.25 for 0.0095M-0.0150M Chitosan-Carrageenan gels improved gelation by the

  1. The effect of multifunctional polymer-based gels on wound healing in full thickness bacteria-contaminated mouse models

    OpenAIRE

    Yates, Cecelia Christina; Whaley, Diana; Babu, Ranjith; Zhang, Jianying; Krishna, Priya; Beckman, Eric; Pasculle, A. William; Wells, Alan

    2007-01-01

    We determined whether a two part space-conforming polyethyleneglycol/dopa polymer-based gel promoted healing of contaminated wounds in mice. This silver-catalysed gel was previously developed to be broadly microbiocidal in vitro while being biocompatible with human wound cell functioning. Full-thickness wounds were created on the backs of mice. The wounds were inoculated with 104 CFU of each of four common skin wound contaminants, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter b...

  2. A NOVEL OPHTHALMIC DRUG DELIVERY SYSTEM: IN-SITU GEL

    Directory of Open Access Journals (Sweden)

    A.P. Patil*, A.A. Tagalpallewar, G.M. Rasve, A.V. Bendre, P.G. Khapekar

    2012-09-01

    Full Text Available The ophthalmic in-situ gels now days proved an palpable sustained drug delivery in various eye diseases. The formulation of in-situ gels for eye which carries the advantages like easy for administration, reduces frequency of dose and improves patient compliance. The formation of in-situ gels depends on phase transition system or sol-gel transition system. The formulation approaches like temperature intonation, pH change and presence of ions from which the drug gets released in a sustained and controlled manner are utilised for in-situ gels. Various polymers that are used for the formulation of in-situ gels include chitosan, Pluronic F-127, poly-caprolactone, gellan gum, alginic acid, xyloglucan, pectin etc.

  3. Study of the relative dose-response of BANG-3[reg] polymer gel dosimeters in epithermal neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Uusi-Simola, J [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Savolainen, S [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Kangasmaeki, A [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Heikkinen, S [Department of Laboratory Diagnostics, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Perkioe, J [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Ramadan, U Abo [Department of Laboratory Diagnostics, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Seppaelae, T [Department of Oncology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Karila, J [Department of Oncology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Seren, T [VTT Processes, Technical Research Centre of Finland, FIN-02044 VTT, Finland (Finland); Kotiluoto, P [VTT Processes, Technical Research Centre of Finland, FIN-02044 VTT, Finland (Finland); Sorvari, P [Department of Laboratory Diagnostics, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Auterinen, I [VTT Processes, Technical Research Centre of Finland, FIN-02044 VTT, Finland (Finland)

    2003-09-07

    Polymer gels have been reported as a new, potential tool for dosimetry in mixed neutron-gamma radiation fields. In this work, BANG-3 (MGS Research Inc.) gel vials from three production batches were irradiated with 6 MV photons of a Varian Clinac 2100 C linear accelerator and with the epithermal neutron beam of the Finnish boron neutron capture therapy (BNCT) facility at the FiR 1 nuclear reactor. The gel is tissue equivalent in main elemental composition and density and its T2 relaxation time is dependent on the absorbed dose. The T2 relaxation time map of the irradiated gel vials was measured with a 1.5 T magnetic resonance (MR) scanner using spin echo sequence. The absorbed doses of neutron irradiation were calculated using DORT computer code, and the accuracy of the calculational model was verified by measuring gamma ray dose rate with thermoluminescent dosimeters and {sup 55}Mn(n,{gamma}) activation reaction rate with activation detectors. The response of the BANG-3 gel dosimeter for total absorbed dose in the neutron irradiation was linear, and the magnitude of the response relative to the response in the photon irradiation was observed to vary between different gel batches. The results support the potential of polymer gels in BNCT dosimetry, especially for the verification of two- or three-dimensional dose distributions.

  4. Evaluation of fibroblasts adhesion and proliferation on alginate-gelatin crosslinked hydrogel.

    Directory of Open Access Journals (Sweden)

    Bapi Sarker

    Full Text Available Due to the relatively poor cell-material interaction of alginate hydrogel, alginate-gelatin crosslinked (ADA-GEL hydrogel was synthesized through covalent crosslinking of alginate di-aldehyde (ADA with gelatin that supported cell attachment, spreading and proliferation. This study highlights the evaluation of the physico-chemical properties of synthesized ADA-GEL hydrogels of different compositions compared to alginate in the form of films. Moreover, in vitro cell-material interaction on ADA-GEL hydrogels of different compositions compared to alginate was investigated by using normal human dermal fibroblasts. Viability, attachment, spreading and proliferation of fibroblasts were significantly increased on ADA-GEL hydrogels compared to alginate. Moreover, in vitro cytocompatibility of ADA-GEL hydrogels was found to be increased with increasing gelatin content. These findings indicate that ADA-GEL hydrogel is a promising material for the biomedical applications in tissue-engineering and regeneration.

  5. 3D dosimetry for complex stereotactic radiosurgery using a tomographic optical density scanner and BANG polymer gels

    International Nuclear Information System (INIS)

    Purpose: Radiation sensitive tissue equivalent BANG polymer gels (MGS Research, Inc., Guilford, CT) have been developed for three dimensional verification of complex radiotherapy treatment plans. This study evaluated the performance of a prototype optical density scanner in verification of a complex radiosurgery treatment plan using linear accelerator based radiosurgery and BANG polymer gel dosimeters. Materials and Methods: BANG polymer gel dosimeters were treated with stereotactic radiosurgery using 6MV photons to single isocenters and to a 3 isocenter radiosurgery plan. Appropriate controls for evaluating the linearity of dose response were irradiated using a water bath and 6MV photons. Two separate methods for imaging the radiation-induced polymerization in the gel were used. The first method, MRI imaging, used the spatial distribution of the NMR transverse relaxation rates (R2) of the water protons in the gel to create a 3D dose map. In the second, a prototype optical density scanner was used to reconstruct a 3D dose distribution from multiple planar images of the gel which were generated using a filtered back-projection algorithm and measurements of optical transmission. Results: Data obtained from MRI imaging and the images generated by the optical scanner were compared with the plan with excellent results. Very close agreement between all three data sets was demonstrated. The BANG polymer gels demonstrated an excellent linearity of response and a very large (∼20 Gray) dynamic range. Conclusion: The ability to permanently record (and interrogate at a later time) integrated 3D dose distributions will be valuable in assessing complex external beam treatment plans such as radiosurgical treatment plans as well as in commissioning and periodic checking of dynamic wedges, multileaf collimators, etc. used for conventionally fractionated conformal radiotherapy. The linearity of response and wide dynamic range are important in the evaluation of radiosurgical

  6. Synthesis of nano-bound microsphere Co3O4 by simple polymer-assisted sol–gel technique

    International Nuclear Information System (INIS)

    Nano-bound Co3O4 microspheres and molten Co3O4 microspheres were synthesized for the first time by a simple polymer (poly-(vinylpyrrolidone))-assisted sol–gel and sol–gel technique, respectively. Thermal decomposition of the precursor samples of both polymer-assisted sol–gel and sol–gel technique were studied by thermogravimetric analysis. In both techniques, the material was calcined at different temperatures for the formation of phase pure Co3O4. X-ray diffraction confirmed the formation of phase pure cubic spinel structured Co3O4 at 400 and 500 °C for the polymer-assisted sol–gel and sol–gel technique, respectively. Fourier transform infrared spectroscopy revealed the vibrational assignments of functional groups associated with the cubic spinel structure of Co3O4. Scanning electron microscopy of all samples showed clear microsphere sizes ranging from 1 to 4 μm. Both techniques allowed the formation of spherical-shaped microspheres by a simple process. Nano-bound microspheres were observed from the polymer-assisted sol–gel technique because the decomposition of PVP at 400 °C is the main reason for the formation of nano-bound microspheres. The nanoparticle size of the nano-bound microsphere measured by transmission electron microscopy was ∼40 nm. Therefore, PVP is an essential compound for the formation of nano-bound microspheres. This very simple and inexpensive technique is suitable for the formation of spherical-shaped microspheres.

  7. Effect of thiolated polymers to textural and mucoadhesive properties of vaginal gel formulations prepared with polycarbophil and chitosan.

    Science.gov (United States)

    Cevher, Erdal; Sensoy, Demet; Taha, Mohamed A M; Araman, Ahmet

    2008-01-01

    The aim of this study was to design and evaluate of mucoadhesive gel formulations for the vaginal application of clomiphene citrate (CLM) for local treatment of human papilloma virus (HPV) infections. Chitosan (CHI) and polycarbophil (PC) were covalently modified using the thioglycolic acid and L-cysteine, respectively. The formation of thiol conjugates of chitosan (CHI-TG) and polycarbophil (PC-CYS) were confirmed by FT-IR analysis and PC-CYS and CHI-TG were found to have 148.42 +/- 4.16 and 41.17 +/- 2.34 micromol of thiol groups per gram of polymer, respectively. One percent CLM gels were prepared by combination of various concentrations of PC and CHI with thiolated conjugates of these polymers. Hardness, compressibility, elasticity, adhesiveness and cohesiveness of the gels were measured by Texture profile analysis and the vaginal mucoadhesion was investigated by mucoadhesion test. The increasing in the amount of the thiol conjugates was found to enhance the elasticity, cohesiveness, adhesiveness and mucoadhesion of the gel formulations but not their hardness and compressibility when compared to gels prepared using their respective parent formulations. Slower release rate of CLM from gels was achieved when the polymer concentrations were increased in the gel formulations. PC and its thiol conjugate were found to prolong the release of CLM longer than 70 h unlike gel formulations prepared using CHI and its thiol conjugate which were able to release CLM up to 12 h. Stability of CLM was preserved during the 3 month stability analysis under controlled room temperature and accelerated conditions.

  8. 海澡酸钙胶囊化重组E.coli BL21(DE3)生产靛蓝%Production of Indigo by Immobilization of E.coli BL21 (DE3) Cells in Calcium- Alginate Gel Capsules

    Institute of Scientific and Technical Information of China (English)

    陆燕; 梅乐和

    2007-01-01

    The ability of catalyzing indole into indigo of gene engineering strain expressing P450 BM3 immobilized by entrapment in calcium-alginate gel capsules was examined, and various characteristics of immobilized cells were assessed.Optimum conditions for cells activity were not affected after immobilization, and pH and temperature for both free and immobilized cells were found to be pH 7.5 and 35℃, respectively.The immobilized cells exhibited a markedly improved thermal stability than free cells.After five repeated experiments, the yield of indigo with the immobilized cells retained over 94% of their original activity, which indicated that the operational stability for recycling in batch processes was improved.

  9. Technological Advance for Alginate Production in Mexico

    OpenAIRE

    Hernández-Carmona G.; Rodríguez-Montesinos Y.E.; Arvizu-Higuera D.L.; Reyes-Tisnado R.; Murillo-Álvarez J.I.; Muñoz-Ochoa M.

    2012-01-01

    Alginates are polysaccharides extracted from brown seaweeds. They are used in food industry, pharmaceutical, textile, among other, because of their properties to give high viscous solution and gel forming. This review describes the optimized process at pilot plant level for alginate production. The process includes washing the algae with HCl at pH 4, extraction of the alginate in Na2CO3 solution at pH 10 and heating to 80oC, dilution of the paste and filtrate with a vacuum rotary filter. Algi...

  10. Ionic transport and electrochemical stability of PVDF-HFP based gel polymer electrolytes

    Science.gov (United States)

    Rosdi, A.; Zainol, N. H.; Osman, Z.

    2016-02-01

    The gel polymer electrolytes (GPEs) samples consisting of polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP), ethylene carbonate (EC) and propylene carbonate (PC) with different concentrations of magnesium triflate salt, Mg(CF3SO3)2 were prepared using the solution casting technique. The ionic conductivity of the GPEs was studied by using a.c impedance spectroscopy and the sample containing 20 wt% salt exhibited the highest conductivity of 5.11 × l0-3 Scm-1. Ionic transport number of the GPEs shows that the samples contain ionic species as main charge carrier while cationic transport number for the highest conducting sample was found to be 0.27. The electrochemical properties of the GPEs were studied using Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV). The GPEs show high electrochemical stability ˜3.5V (versus Mg2+/Mg) where the highest conducting sample exhibited the highest stability.

  11. STUDY OF THE DIGESTED SLUDGE DEWATERING EFFECTIVENESS USING POLYELECTROLYTE GEL BASED ON ORGANIC POLYMERS

    Directory of Open Access Journals (Sweden)

    Marcin Głodniok

    2016-02-01

    Full Text Available The paper addresses the problems connected with sewage sludge dewatering. The premise of the study was the analysis of whether there are opportunities to increase the efficiency of dewatering sludge, a relatively low-cost involving the use of innovative polymers. The authors analyzed the impact of the new type of polyelectrolyte gel on the effectiveness of dewatering sludge. Laboratory studies were carried out at polyelectrolyte dose selection and laboratory testing on the press chamber designed to simulate the actual operation of sludge dewatering system. Two different doses of polyelectrolyte were tested for dose I – 4 ml/m3 and dose II – 8 ml/m3. The conducted analysis on laboratory press showed an increase of sludge dewatering efficiency by about 2% for dose no. I and by about 13% for dose no. II, in comparison to the test without polyelectrolyte.

  12. Magnetic resonance and conductivity study of a gelatin-based polymer gel electrolyte

    International Nuclear Information System (INIS)

    This work reports results from proton nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) and complex impedance spectroscopy of gelatin-based polymer gel electrolytes containing chloridric acid, cross-linked with formaldehyde and plasticized with glycerol. Ionic conductivity of 4 × 10−5 S/cm were obtained at room temperature for samples prepared with 0.1 M of HCl. Proton (1H) lineshapes and spin-lattice relaxation times were measured as a function of temperature. Activation energies extracted from the 1H NMR relaxation data are in the range of 23–25 kJ/mol. The EPR spectra, which were carried out in samples doped with copper perchlorate, were interpreted with the aid of an axial spin Hamiltonian and indicate the presence of two different Cu2+ species in axially distorted sites. Copper complexation with both hydrogen and nitrogen was verified by electron spin-echo envelope modulation (ESEEM) techniques.

  13. Rheological and textural properties of microemulsion-based polymer gels with indomethacin.

    Science.gov (United States)

    Froelich, Anna; Osmałek, Tomasz; Kunstman, Paweł; Roszak, Rafał; Białas, Wojciech

    2016-01-01

    In this paper, we present novel microemulsion (ME)-based semisolid polymer gels designed for topical administration of poorly water soluble non-steroidal anti-inflammatory drugs. Indomethacin (IND) was used as a model compound. The ME consisted of castor oil, water, Tween®80 as a surfactant and ethanol as cosurfactant. To obtain the desired consistency of the formulations Carbopol®960 was applied as a thickening agent. The aim of the study was to analyze in detail the mechanical properties of the obtained systems, with special attention paid to the features crucial for topical application. The rheological and textural experiments performed for samples with and without the incorporated drug clearly indicate that flow characteristics, viscoelastic properties and texture profiles were affected by the presence of IND. Novel semisolid formulations with IND described for the first time in this paper can be considered as an alternative for commercially available conventional topical dosage forms. PMID:26204348

  14. Incorporating multislice imaging into x-ray CT polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, H., E-mail: holly.johnston@utsw.edu [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2 (Canada); Hilts, M. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada and Medical Physics, BC Cancer Agency, Vancouver Island Centre, Victoria, British Columbia V8R 6V5 (Canada); Jirasek, A. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada and Department of Physics, University of British Columbia—Okanagan Campus, Kelowna, British Columbia V1V 1V7 (Canada)

    2015-04-15

    Purpose: To evaluate multislice computed tomography (CT) scanning for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD) and to establish a baseline assessment of image noise and uniformity in an unirradiated gel dosimeter. Methods: A 16-slice CT scanner was used to acquire images through a 1 L cylinder filled with water. Additional images were collected using a single slice machine. The variability in CT number (N{sub CT}) associated with the anode heel effect was evaluated and used to define a new slice-by-slice background subtraction artifact removal technique for CT PGD. Image quality was assessed for the multislice system by evaluating image noise and uniformity. The agreement in N{sub CT} for slices acquired simultaneously using the multislice detector array was also examined. Further study was performed to assess the effects of increasing x-ray tube load on the constancy of measured N{sub CT} and overall scan time. In all cases, results were compared to the single slice machine. Finally, images were collected throughout the volume of an unirradiated gel dosimeter to quantify image noise and uniformity before radiation is delivered. Results: Slice-by-slice background subtraction effectively removes the variability in N{sub CT} observed across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image noise was higher for the multislice system compared to the single slice scanner, but overall image quality was comparable between the two systems. Further study showed N{sub CT} was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thicknesses examined. In addition, the multislice system was found to eliminate variations in N{sub CT} due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to

  15. Electrochemical Impedance Spectroscopy Studies of Magnesium-Based Polymethylmethacrylate Gel Polymer Electroytes

    International Nuclear Information System (INIS)

    Magnesium-based rechargeable batteries might be an interesting future alternative to lithium-based batteries since magnesium compounds are highly abundant in the earth and are environmental friendly. In this work, we have prepared polymethylmethacrylate (PMMA) based gel polymer electrolyte (GPE) films containing two different magnesium salts, which is magnesium triflate, Mg(CF3SO3)2 and magnesium perchlorate, Mg(ClO4)2 using solution casting technique. The ionic conductivity of both gel polymer electrolyte systems was evaluated using a.c impedance spectroscopy. Results show that at room temperature, GPE-Mg(CF3SO3)2 system exhibits the highest conductivity value at 1.27 × 10−3 S cm−1 for the film containing 20 wt.% of Mg(CF3SO3)2 salt, while the highest conductivity value for the GPE-Mg(ClO4)2 system is 3.13 × 10−3 S cm−1 for the film containing 15 wt.% of Mg(ClO4)2 salt. The conductivity-temperature studies of both GPE systems follow the Arrhenius behavior. The activation energies for ionic conduction were determined to be in the range of 0.18–0.26 eV. The transport numbers of magnesium ions in both GPE systems were evaluated using the combination of a.c impedance spectroscopy and d.c polarization techniques. The results obtained indicate that the charge carriers in the GPE films for both systems are predominantly due to ions

  16. Dye-sensitized solar cell with poly(acrylic acid-co-acrylonitrile)-based gel polymer electrolyte

    International Nuclear Information System (INIS)

    Highlights: ► A nontoxic, easily synthesized poly(acrylic acid-co-acrylonitrile) showed suitable transmittance for dye-sensitized solar cell. ► A cell with relatively large active area fabricated with this polymer material showed acceptable efficiency. ► The gel polymer matrix affected the charge recombination, I3− diffusion, double layer capacitance, and electron lifetime in the cell. - Abstract: A non-conducting, nontoxic poly(acrylic acid-co-acrylonitrile) (PAA) was prepared and used as a supporting matrix for the electrolyte of dye-sensitized solar cells (DSSCs). DSSCs of active area 0.80 cm × 1.10 cm fabricated with PAA, 0.5 M LiI, 0.05 M I2, 0.5 M 3-tert-butylpyridine, and 0.1 M 1-methyl-3-propylimidazolium iodide in 3-methoxypropionitrile solvent showed an average solar energy conversion efficiency of 1.61% under simulated sunlight illumination of 100 mW cm−2, AM 1.5. The effects of the gel polymer matrix on the electrochemical properties of DSSCs were studied using the electrochemical impedance spectroscopy. Relative to the non-gel reference cells, the results showed a decrease in charge recombination, ionic diffusion, and double layer capacitance and an increase in electron lifetime. These results could play an important role in determining the future direction for the development of high-performance gel polymer electrolytes.

  17. Technological Advance for Alginate Production in Mexico

    Directory of Open Access Journals (Sweden)

    Hernández-Carmona G.

    2012-04-01

    Full Text Available Alginates are polysaccharides extracted from brown seaweeds. They are used in food industry, pharmaceutical, textile, among other, because of their properties to give high viscous solution and gel forming. This review describes the optimized process at pilot plant level for alginate production. The process includes washing the algae with HCl at pH 4, extraction of the alginate in Na2CO3 solution at pH 10 and heating to 80oC, dilution of the paste and filtrate with a vacuum rotary filter. Alginate precipitation is carried out by adding CaCl2 filtration. The fibers obtained are treated with HCl to obtain alginic acid. The product is neutralized with Na2CO3 to obtain sodium alginate. The product is dried with hot air, milled, and screened at different mesh sizes. We described the different products obtained and their physical and chemical properties. Finally, costs and barriers found that limit the alginate production at commercial level in Mexico are discussed, including the lack of the industrial design, the international cost of the alginates, the policy to give the seaweeds beds concessions, and the role of the investors.

  18. Whisker formation of $\\pi$-stacking long polymers: Gel transition in absence of mechanically percolating structures

    CERN Document Server

    Villalobos, Gabriel

    2016-01-01

    We present numerical evidence showing a gel transition occurring in the absence of mechanically percolating structures. The system under consideration consists of long slender laths who interact mostly in the direction perpendicular to their areas; self-assembling into ordered aggregates. An example of such system, which inspired this project, is the poly 3 hexylthiophene (P3HT); a polymer used in the construction of solar cells. In this context, the ordered aggregates are known as whiskers. In order to do the numerical oscillatory shear experiments, we have developed a Brownian dynamics model, in which the potential depends on the orientation of the particles, Brownian Orientational Lath moDel (BOLd). It is characterized by a potential energy that depends both on the angle between orientation vectors, along the long axis of the laths, as well as the vectors normal to the plane of the laths; and which has only one energetic parameter. The storage and loss modulus measured here shown the gel transition, even t...

  19. Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    S. N. F. Yusuf

    2014-01-01

    Full Text Available Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr4NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC, 3.17 wt.% propylene carbonate (PC, 19.0 wt.% of Pr4NI, and 1.9 wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 × 10−3 S cm−1. The dye-sensitized solar cell (DSSC fabricated with this electrolyte exhibits an efficiency of 3.5% with JSC of 7.38 mA cm−2, VOC of 0.72 V, and fill factor of 0.66. When various amounts of lithium iodide (LiI were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr4NI : LiI is 2 : 1. This cell has JSC, VOC and fill factor of 7.25 mA cm−2, 0.77 V and 0.67, respectively.

  20. Molecularly imprinted polymer for 2, 4-dichlorophenoxyacetic acid prepared by a sol-gel method

    Indian Academy of Sciences (India)

    Yanli Sun

    2014-07-01

    Based on a sol-gel procedure, a molecularly imprinted polymer (MIP) for 2, 4-dichlorophenoxyacetic acid (2, 4-D) was synthesized, using phenyltrimethoxysilane (PTMOS), aminopropyltriethoxysilane (APTES) as monomers and tetraethoxysilane (TEOS) as cross-linking agent. In addition to the amount of the template, some factors in the sol-gel process: TEOS/APTES/PTMOS molar ratio, H2O/Si molar ratio, CH3CH2OH/Si molar ratio, etc. were investigated in detail. Results show that the optimum conditions for the preparation of the MIPs were 20:1.5:1 (TEOS: APTES: PTMOS), ca. 4 (H2O/Si), ca. 4 (CH3CH2OH/Si), respectively. Effects of various parameters involved in the adsorption process of 2, 4-D on MIP such as incubation time, pH, etc. were also evaluated. It is found that the adsorption attained equilibrium within 3 h, the optimum pH for adsorption was about 7 and the adsorption obeyed Langmuir model. Test results also demonstrated that the present MIP for 2, 4-D had large adsorption capacity (the maximum adsorption concluded from Langmuir model reached 243.3 mg/g) and good selectivity.

  1. Molecular structure effects on the post irradiation diffusion in polymer gel dosimeters

    International Nuclear Information System (INIS)

    Polymer gel dosimeters have specific advantages for recording 3D radiation dose distribution representing a key factor for most of the therapeutic and diagnostic radiation techniques. Radiation-induced polymerization and crosslinking reactions that take place in the dosimeter have been studied for different monomers like acrylamide and N,N-methylene-bis acrylamide (Bis) and most recently for less toxic monomers like N-isopropylacrylamide and Bis. In this work a novel system based on itaconic acid and Bis is proposed, the radical polymerization or gel formation of these monomers has been already studied for the formation of an hydrogel for non dosimetric applications and their reactivity are comparable with the already mentioned systems. Although the 3D structure is maintained after the dosimeter has been irradiated, it is not possible to eliminate the diffusion of the reacted and monomer species in regions of dose gradients within the gel after irradiation. As a consequence the dose information of the dosimeters loose quality over time. The mobility within the gelatin structure of the already mentioned species is related to their chemical structure, and nature. In this work the effect of changes in the chemical structure of the monomers over the dosimetric sensitivity and over the post-irradiation diffusion of species is studied. One of the acrylic acid groups of the itaconic acid molecule is modified to obtain molecules with similar reactivity but different molecular sizes. Dosimetric systems with these modified species, Bis, an antioxidant to avoid oxygen polymerization inhibition, water and gelatin are irradiated in an X-ray tomography at different doses, and the resulting dosimeters are characterized by Raman spectroscopy and optical absorbance to study their feasibility and capabilities as dosimetric systems, and by optical-CT to analyze the diffusion degree after being irradiated. (Author)

  2. Molecular structure effects on the post irradiation diffusion in polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Mattea, F.; Romero, M.; Strumia, M. [Instituto Multidisciplinario de Biologia Vegetal / CONICET, Universidad Nacional de Cordoba, Departamento de Quimica Organica, Ciudad Universitaria, 5000 Cordoba (Argentina); Vedelago, J. [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Quiroga, A. [Centro de Investigacion y Estudios de Matematica / CONICET, Oficina 318 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Valente, M., E-mail: fmattea@gmail.com [Instituto de Fisica E. Gaviola / CONICET, LIIFAMIRx, Oficina 102 FaMAF - UNC, 5000 Cordoba (Argentina)

    2014-08-15

    Polymer gel dosimeters have specific advantages for recording 3D radiation dose distribution representing a key factor for most of the therapeutic and diagnostic radiation techniques. Radiation-induced polymerization and crosslinking reactions that take place in the dosimeter have been studied for different monomers like acrylamide and N,N-methylene-bis acrylamide (Bis) and most recently for less toxic monomers like N-isopropylacrylamide and Bis. In this work a novel system based on itaconic acid and Bis is proposed, the radical polymerization or gel formation of these monomers has been already studied for the formation of an hydrogel for non dosimetric applications and their reactivity are comparable with the already mentioned systems. Although the 3D structure is maintained after the dosimeter has been irradiated, it is not possible to eliminate the diffusion of the reacted and monomer species in regions of dose gradients within the gel after irradiation. As a consequence the dose information of the dosimeters loose quality over time. The mobility within the gelatin structure of the already mentioned species is related to their chemical structure, and nature. In this work the effect of changes in the chemical structure of the monomers over the dosimetric sensitivity and over the post-irradiation diffusion of species is studied. One of the acrylic acid groups of the itaconic acid molecule is modified to obtain molecules with similar reactivity but different molecular sizes. Dosimetric systems with these modified species, Bis, an antioxidant to avoid oxygen polymerization inhibition, water and gelatin are irradiated in an X-ray tomography at different doses, and the resulting dosimeters are characterized by Raman spectroscopy and optical absorbance to study their feasibility and capabilities as dosimetric systems, and by optical-CT to analyze the diffusion degree after being irradiated. (Author)

  3. Influence of the Ionic Liquid Type on the Gel Polymer Electrolytes Properties

    Directory of Open Access Journals (Sweden)

    Juan P. Tafur

    2015-11-01

    Full Text Available Gel Polymer Electrolytes (GPEs composed by ZnTf2 salt, poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP, and different ionic liquids are synthesized using n-methyl-2-pyrrolidone (NMP as solvent. Three different imidazolium-based ionic liquids containing diverse cations and anions have been explored. Structural and electrical properties of the GPEs varying the ZnTf2 concentration are analyzed by ATR-FTIR, DSC, TG, and cyclic voltammetry. Free salt IL-GPEs present distinct behavior because they are influenced by the different IL cations and anions composition. However, inclusion of ZnTf2 salt inside the polymers provide GPEs with very similar characteristics, pointing out that ionic transport properties are principally caused by Zn2+ and triflate movement. Whatever the IL used, the presence of NMP solvent inside the polymer’s matrix turns out to be a key factor for improving the Zn2+ transport inside the GPE due to the interaction between Zn2+ cations and carbonyl groups of the NMP. High values of ionic conductivity, low activation energy values, and good voltammetric reversibility obtained regardless of the ionic liquid used enable these GPEs to be applied in Zn batteries. Capacities of 110–120 mAh·g−1 have been obtained for Zn/IL-GPE/MnO2 batteries discharged at −1 mA·cm−2.

  4. Dye-sensitized solar cell with natural gel polymer electrolytes and f-MWCNT as counter-electrode

    Science.gov (United States)

    Nwanya, A. C.; Amaechi, C. I.; Ekwealor, A. B. C.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

    2015-05-01

    Samples of DSSCs were made with gel polymer electrolytes using agar, gelatin and DNA as the polymer hosts. Anthocyanine dye from Hildegardia barteri flower is used to sensitize the TiO2 electrode, and the spectrum of the dye indicates strong absorptions in the blue region of the solar spectrum. The XRD pattern of the TiO2 shows that the adsorption of the dye did not affect the crystallinity of the electrode. The f-MWCNT indicates graphite structure of the MWCNTs were acid oxidized without significant damage. Efficiencies of 3.38 and 0.1% were obtained using gelatin and DNA gel polymer electrolytes, respectively, for the fabricated dye-sensitized solar cells.

  5. 7Li nuclear magnetic resonance studies of dynamics in a ternary gel polymer electrolyte based on polymeric ionic liquids

    International Nuclear Information System (INIS)

    The influence of the polymeric ionic liquid (PIL) Poly(diallyldimethylammonium bis(trifluoromethylsulfonyl) imide) (PDADMATFSI) on the lithium dynamics was investigated in a ternary gel polymer electrolyte consisting of PDADMATFSI as stabilizing polymer, ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, P14TFSI) and lithium salt (lithium bis(trifluoromethylsulfonyl) imide, LiTFSI). The diffusion coefficient of the lithium ions is investigated by pulsed-field-gradient NMR, the conductivity of the electrolyte is determined by impedance spectroscopy. The local lithium dynamics is characterized by 7Li spin lattice relaxation rates (R1). The relaxation rates are well described by Blombergen-Purcell-Pound (BPP) theory at all polymer concentrations (up to 45 mol%), implying that the Li dynamics is governed by one single motional mode. Interestingly, activation energies for this motion decrease from 20 kJ/mol to 15 kJ/mol with increasing polymer content and are independent on the salt content. We thus conclude that the polymer is interacting with the anion coordination shell, which is accompanied by a very beneficial effect on the local lithium dynamics, as the polymer PDADMATFSI reduces the Li-TFSI interactions. This result is promising for further investigations for potential use of PDADMATFSI-containing gels as electrolytes in energy storage devices

  6. Evaluation of the Effects of Inhomogeneities on Dose Profiles Using Polymer Gel Dosimeter and Monte Carlo Simulation in Gamma Knife

    Directory of Open Access Journals (Sweden)

    Tayeb Allahverdi Pourfallah

    2012-03-01

    Full Text Available Introduction Polymer gel dosimeters offer a practical solution to 3D dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. In this study, EGSnrc calculated and PAGAT polymer gel dosimeter measured dose profiles from single shot irradiation with 18 mm collimator of Gamma Knife in homogeneous and inhomogeneous phantoms were compared with each other. Materials and Methods The head phantom was a custom-built 16 cm diameter plexiglas sphere. Inside the phantom, there were two cubic cutouts for inserting the gel vials and inhomogeneities. Following irradiation with the Gamma Knife unit, the polymer gel dosimeters were scanned with a 1.5 T MRI scanner. For the purpose of simulation the simplified channel of 60Co source of Gamma Knife BEAMnrc and for extracting the 3D dose distribution in the phantom, DOSXYZnrc codes were used. Results Within high isodose levels (>80%, there are dose differences higher than 7%, especially between air inserted and PTFE inserted phantoms, which were obtained using both simulation and experiment. This means that these values exceed the acceptance criterion of conformal radiotherapy and stereotactic radiosurgery (i.e., within some isodose levels, less than 93% of prescription dose are delivered to the target. Conclusion The discrepancies observed between the results obtained from heterogeneous and homogeneous phantoms suggest that Leksell Gamma Knife planning system (LGP predictions which assume the target as a homogeneous material must be corrected in order to take care of the air- and bone-tissue inhomogeneities.

  7. Hierarchical Sol-Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, Yuzo; Ueki, Takeshi; McIntosh, Lucas D.; Tamura, Saki; Niitsuma, Kazuyuki; Imaizumi, Satoru; Lodge, Timothy P.; Watanabe, Masayoshi (U of Tokyo); (UMM); (Yokohama)

    2016-04-29

    Here we investigate a hierarchical morphology change and accompanying sol–gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEtMA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the self-assembly of each of the thermosensitive blocks in the IL, and a sol–gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20 wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. For each phase was formed reversibly and rapidly over the corresponding temperature range. Finally, the jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).

  8. Photo-activated ionic gelation of alginate hydrogel: real-time rheological monitoring of the two-step crosslinking mechanism.

    Science.gov (United States)

    Higham, Alina K; Bonino, Christopher A; Raghavan, Srinivasa R; Khan, Saad A

    2014-07-21

    We examine the gelation of alginate undergoing ionic crosslinking upon ultraviolet (UV) irradiation using in situ dynamic rheology. Hydrogels are formed by combining alginate with calcium carbonate (CaCO3) particles and a photoacid generator (PAG). The PAG is photolyzed upon UV irradiation, resulting in the release of free calcium ions for ionic crosslinking. The viscous and elastic moduli during gelation are monitored as a function of the UV irradiation intensity, exposure time, alginate concentration, and the ratio between alginate and calcium carbonate. Gel time decreases as irradiation intensity increases because a larger concentration of PAG is photolyzed. Interestingly, dark curing, the continuing growth of microstructure in the absence of UV light, is observed. In some instances, the sample transitions from a solution to a gel during the dark curing phase. Additionally, when exposed to constant UV irradiation after the dark curing phase, samples reach the same plateau modulus as samples exposed to constant UV without dark curing, implying that dark curing does not affect the gelation mechanism. We believe the presence of dark curing is the result of the acidic environment persisting within the sample, allowing CaCO3 to dissociate, thereby releasing free Ca(2+) ions capable of binding with the available appropriate ionic blocks of the polymer chains. The growth of microstructure is then detected if the activation barrier has been crossed to release sufficient calcium ions. In this regard, we calculate a value of 30 J that represents the activation energy required to initiate gelation. PMID:24894636

  9. Novel configuration of poly(vinylidenedifluoride)-based gel polymer electrolyte for application in lithium-ion batteries

    Science.gov (United States)

    Fasciani, Chiara; Panero, Stefania; Hassoun, Jusef; Scrosati, Bruno

    2015-10-01

    Herein we propose a novel poly(vinylidene difluoride) (PVdF)-based gel polymer electrolyte (GPE) for application in lithium-ion batteries, LIBs. The GPE is prepared under air as a dry, flexible film and directly gelled during LIB assembly with a conventional liquid organic electrolyte. The dry-gel here originally reported maintains its structural integrity due to the presence of crystallized EC-solvent within its matrix that avoids structural collapse, as demonstrated by TGA analysis. By avoiding the use of controlled atmosphere, the GPE is easy to handle and suitable for roll-to-roll scaling-up, i.e. characteristics missed by the common gel membranes. Scanning Electron Microscopy (SEM) evidences a micrometric polymer network of the dry membrane precursor acting as the support matrix for the gelation. Electrochemical impedance spectroscopy (EIS) measurements and galvanostatic tests suggest a good stability of the lithium electrode/gel electrolyte interface and a satisfactory lithium transference number. Cycling tests of gel-electrolyte-based lithium half-cells using lithium iron phosphate (LiFePO4, LFP) and graphite (C), respectively, as counter electrodes, as well as of a full C/LFP lithium-ion battery confirm the suitability of the GPE developed in this work for application in stable, low cost and environmentally friendly energy storage systems.

  10. High resolution polymer gel dosimetry for small beam irradiation using a 7T micro-MRI scanner

    Energy Technology Data Exchange (ETDEWEB)

    Ding Xuanfeng; Olsen, John; Best, Ryan; Bennett, Marcus; McGowin, Inna; Dorand, Jennifer; Link, Kerry; Bourland, J Daniel, E-mail: dingx6@wfu.ed

    2010-11-01

    The use of small field radiation beams has greatly increased with advanced radiation therapy techniques such as IMRT, rotational IMRT, and stereotactic body radiotherapy. In this work small field 3D dose distributions have been measured with high spatial resolution using polymer gels and 7T micro-MR imaging. A MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) polymer gel {sup [1]} phantom was used to capture the 3D dose distributions for two small field (5 x 5 mm{sup 2} and 10 x 10 mm{sup 2}) for a 6MV x-ray beam. High resolution 3D T2 maps were obtained with 7T micro-MRI (0.156mm x 0.156mm x 1mm, MSME pulse sequence). For comparison T2 maps, the gel phantom was scanned in a 3T MRI clinical scanner (0.254mm x 0.254mm x 2mm, FSE pulse sequence). Normalized 3D dose maps were calculated in Matlab. Results show that 7T micro-MRI 3D gel dosimetry measurements are much more stable, less noisy, and have higher spatial resolution than those obtained using a 3T clinical scanner for the same amount of scan time. In general, 3D gel dosimetry results also agree with simultaneously-obtained radiochromic film dosimetry. This study indicates that the MAGIC polymer gel with 7T micro-MRI for 3D dose readout could potentially be used for small radiation beams, including measurements for micro-beams (field size {approx} 100um).

  11. Gel polymer electrolyte lithium-ion cells with improved low temperature performance

    Energy Technology Data Exchange (ETDEWEB)

    Smart, M.C.; Ratnakumar, B.V.; Behar, A.; Whitcanack, L.D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Yu, J.-S. [LG Chem/Research Park, P.O. Box 61Yu Song, Science Town, Daejon (Korea); Alamgir, M. [Compact Power, Inc., 1857 Technology Drive, Troy, MI 48083 (United States)

    2007-03-20

    For a number of NASA's future planetary and terrestrial applications, high energy density rechargeable lithium batteries that can operate at very low temperature are desired. In the pursuit of developing Li-ion batteries with improved low temperature performance, we have also focused on assessing the viability of using gel polymer systems, due to their desirable form factor and enhanced safety characteristics. In the present study we have evaluated three classes of promising liquid low-temperature electrolytes that have been impregnated into gel polymer electrolyte carbon-LiMn{sub 2}O{sub 4}-based Li-ion cells (manufactured by LG Chem. Inc.), consisting of: (a) binary EC + EMC mixtures with very low EC-content (10%), (b) quaternary carbonate mixtures with low EC-content (16-20%), and (c) ternary electrolytes with very low EC-content (10%) and high proportions of ester co-solvents (i.e., 80%). These electrolytes have been compared with a baseline formulation (i.e., 1.0 M LiPF{sub 6} in EC + DEC + DMC (1:1:1%, v/v/v), where EC, ethylene carbonate, DEC, diethyl carbonate, and DMC, dimethyl carbonate). We have performed a number of characterization tests on these cells, including: determining the rate capacity as a function of temperature (with preceding charge at room temperature and also at low temperature), the cycle life performance (both 100% DOD and 30% DOD low earth orbit cycling), the pulse capability, and the impedance characteristics at different temperatures. We have obtained excellent performance at low temperatures with ester-based electrolytes, including the demonstration of >80% of the room temperature capacity at -60 C using a C/20 discharge rate with cells containing 1.0 M LiPF{sub 6} in EC + EMC + MB (1:1:8%, v/v/v) (MB, methyl butyrate) and 1.0 M LiPF{sub 6} in EC + EMC + EB (1:1:8%, v/v/v) (EB, ethyl butyrate) electrolytes. In addition, cells containing the ester-based electrolytes were observed to support 5C pulses at -40 C, while still

  12. Three-Dimensional Nanoporous Cellulose Gels as a Flexible Reinforcement Matrix for Polymer Nanocomposites.

    Science.gov (United States)

    Shi, Zhuqun; Huang, Junchao; Liu, Chuanjun; Ding, Beibei; Kuga, Shigenori; Cai, Jie; Zhang, Lina

    2015-10-21

    With the world's focus on utilization of sustainable natural resources, the conversion of wood and plant fibers into cellulose nanowhiskers/nanofibers is essential for application of cellulose in polymer nanocomposites. Here, we present a novel fabrication method of polymer nanocomposites by in-situ polymerization of monomers in three-dimensionally nanoporous cellulose gels (NCG) prepared from aqueous alkali hydroxide/urea solution. The NCG have interconnected nanofibrillar cellulose network structure, resulting in high mechanical strength and size stability. Polymerization of the monomer gave P(MMA/BMA)/NCG, P(MMA/BA)/NCG nanocomposites with a volume fraction of NCG ranging from 15% to 78%. SEM, TEM, and XRD analyses show that the NCG are finely distributed and preserved well in the nanocomposites after polymerization. DMA analysis demonstrates a significant improvement in tensile storage modulus E' above the glass transition temperature; for instance, at 95 °C, E' is increased by over 4 orders of magnitude from 0.03 MPa of the P(MMA/BMA) up to 350 MPa of nanocomposites containing 15% v/v NCG. This reinforcement effect can be explained by the percolation model. The nanocomposites also show remarkable improvement in solvent resistance (swelling ratio of 1.3-2.2 in chloroform, acetone, and toluene), thermal stability (do not melt or decompose up to 300 °C), and low coefficients of thermal expansion (in-plane CTE of 15 ppm·K(-1)). These nanocomposites will have great promising applications in flexible display, packing, biomedical implants, and many others. PMID:26397710

  13. Effects of refractive index mismatch in optical CT imaging of polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Manjappa, Rakesh; Makki S, Sharath; Kanhirodan, Rajan, E-mail: rajan@physics.iisc.ernet.in [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Kumar, Rajesh [Radiological Physics and Advisory Division, BARC, Mumbai 400094 (India)

    2015-02-15

    Purpose: Proposing an image reconstruction technique, algebraic reconstruction technique-refraction correction (ART-rc). The proposed method takes care of refractive index mismatches present in gel dosimeter scanner at the boundary, and also corrects for the interior ray refraction. Polymer gel dosimeters with high dose regions have higher refractive index and optical density compared to the background medium, these changes in refractive index at high dose results in interior ray bending. Methods: The inclusion of the effects of refraction is an important step in reconstruction of optical density in gel dosimeters. The proposed ray tracing algorithm models the interior multiple refraction at the inhomogeneities. Jacob’s ray tracing algorithm has been modified to calculate the pathlengths of the ray that traverses through the higher dose regions. The algorithm computes the length of the ray in each pixel along its path and is used as the weight matrix. Algebraic reconstruction technique and pixel based reconstruction algorithms are used for solving the reconstruction problem. The proposed method is tested with numerical phantoms for various noise levels. The experimental dosimetric results are also presented. Results: The results show that the proposed scheme ART-rc is able to reconstruct optical density inside the dosimeter better than the results obtained using filtered backprojection and conventional algebraic reconstruction approaches. The quantitative improvement using ART-rc is evaluated using gamma-index. The refraction errors due to regions of different refractive indices are discussed. The effects of modeling of interior refraction in the dose region are presented. Conclusions: The errors propagated due to multiple refraction effects have been modeled and the improvements in reconstruction using proposed model is presented. The refractive index of the dosimeter has a mismatch with the surrounding medium (for dry air or water scanning). The algorithm

  14. Final Technical Report for 'Investigations of the Role of Protozoa in Transformations of Marine Biopolymers using Phaeocytis Polymer Gels as a Model'

    Energy Technology Data Exchange (ETDEWEB)

    Lessard, Evelyn

    2003-04-01

    OAK B188 Biopolymers and biopolymer gels are major components of the organic carbon and nitrogen pools in the ocean. The overall goal of this project was to better understand the chemical and physical transformations of polymers and polymer gels in coastal waters that are mediated by protists and bacteria. Bacteria are thought to be the major consumers of marine biopolymers, but direct consumption by protists, and the interactions of bacteria and protists, may also be important but largely unexplored pathways of biopolymer cycling. Phaeocystis is a colonial prymnesiophyte alga that produces large amounts of polymer gels that have similar properties to those found in the dissolved organic carbon (DOC) pool namely, they are tangled networks of polymers held together by calcium bridges. We used the polymers and polymer gels produced by two species of Phaeocystis (from the North Atlantic and Antarctica) as models to examine the consumption, degradation and alteration of algal polymer gels by protists and bacteria. We developed several novel methods and approaches to examine polymer gel transformations. One tool was an immunoassay (ELISA) using a polyclonal antibody specific to Phaeocystis polymers that allowed us to track the polymer gels in situ and in laboratory experiments. We successfully tested the ability of the immunoassay to detect and quantify Phaeocystis polymer carbon in water from the Ross Sea, Gulf of Alaska and North Water (Greenland). This exciting new approach demonstrates the usefulness of antibodies for detecting and quantifying a specific component of the DOM pool in natural samples and provides a method for following the sources and sinks of that component. We also developed a fluorescent immunoassay procedure with the antibody to visualize and quantify ingested polymers in single protist cells. In experiments with polymer gels as the sole organic source (no prey), prey plus polymer gels, and prey without polymer gels, we determined that some

  15. Developing stable, low impedance interface between metallic lithium anode and polyacrylonitrile-based polymer gel electrolyte by preliminary voltage cycling

    Energy Technology Data Exchange (ETDEWEB)

    Sotomura, Tadashi; Adachi, Kinichi [Matsushita Electric Industrial Co. Ltd., Moriguchi, Osaka (Japan). Central Research Lab.; Taguchi, Makoto; Iwaku, Masahiro; Tatsuma, Tetsu; Oyama, Noboru [Tokyo Univ. of Agriculture and Technolgy (Japan). Dept. of Applied Chemistry

    1999-09-01

    The metallic lithium anode surface facing to a gel-like polyacrylonitrile polymer electrolyte (gel-SPE) was tried to be stabilized by preliminary voltage cycling. Through voltage cycling from +0.5 to -0.5 V at a scan rate of 10 mV/s at 20 C immediately after assembling a cell having a configuration of Li/gel-SPE/Li, the cell impedance at 100 Hz was kept below 100 {omega} for the cells with a gel-SPE containing LiBF{sub 4} over 230 days at 20 C. The cells with a gel-SPE containing LiPF{sub 6} required preliminary voltage cycling at a voltage higher than 0.5 V and at an elevated temperature of 60 C to obtain and keep a lower impedance during storage. The impedance at 10 kHz which represented the bulk resistance of gel-SPE was almost the same for both cells and constant during storage, around 15 {omega}. This was confirmed in the cell of Li/gel-SPE/DMcT + polyaniline composite cathode (DMcT=2,5-dimercapto-1,3,4-thiadiazole). The metallic lithium anode surface before and after the voltage cycling was subjected to X-ray photoelectron spectroscopy (XPS) analysis: Li{sub 2}CO{sub 3} disappeared and LiF-LiOH remained in the surface layer after the voltage cycling for the LiBF{sub 4} gel-SPE cell while for the LiPF{sub 6} gel-SPE cell, a dense and thin LiF surface layer was broken into a thicker LiF-LiOH layer. The layer consisting of mainly LiF and LiOH which was formed by preliminary voltage cycling was considered to stabilize the interface. (orig.)

  16. A 3,3′-dichlorobenzidine-imprinted polymer gel surface plasmon resonance sensor based on template-responsive shrinkage

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Chunyan; Gao, Jigang, E-mail: gjg@sdau.edu.cn; Zhang, Lili; Zhou, Jie, E-mail: zhoujie@sdau.edu.cn

    2014-02-17

    Graphical abstract: -- Highlights: •Based on template-responsive shrinkage of imprinted gel film, a novel surface plasmon resonance (SPR) sensor is prepared. •The relevant electrochemical parameters are optimized. •The imprinted gel-SPR system has great capability for providing highly sensitive and selective analysis of 3,3′-dichlorobenzidine. •The present SPR sensor was successfully employed to detect 3,3′-dichlorobenzidine in tap water and soil samples. -- Abstract: Molecularly imprinted polymer gel film on the gold substrate of a chip was prepared with minute amount of cross-linker for the fabrication of a surface plasmon resonance (SPR) sensor sensitive to 3,3′-dichlorobenzidine. The molecularly imprinted gel film was anchored on a gold chip by a surface-bound photo-radical initiator. The sensing of 3,3′-dichlorobenzidine is based on responsive shrinkage of the imprinted polymer gel film that is triggered by target binding. This change can improve the responsiveness of the imprinted SPR sensor to 3,3′-dichlorobenzidine. The molecularly imprinted polymer gel film was characterized with contact angle measurements, electrochemical impedance spectroscopy, cyclic voltammogram, swelling measurements and atomic force microscopy. The changes of SPR spectroscopy wavenumber shifts revealed that the imprinted gel sensing film can ‘memorize’ the binding of 3,3′-dichlorobenzidine compared to non-imprinted one. The imprinted gel-SPR sensor showed a linear response in the range of 9.0 × 10{sup −12} to 5.0 × 10{sup −10} mol L{sup −1} (R{sup 2} = 0.9998) for the detection of 3,3′-dichlorobenzidine, and it also exhibited high selectivity to 3,3′-dichlorobenzidine compared to its structurally related analogues. We calculated the detection limits to be 0.471 ng L{sup −1} for tap water and 0.772 ng kg{sup −1} for soil based on a signal to noise ratio of 3. The method showed good recoveries and precision for the samples spiked with 3,3

  17. An investigation of agitation speed as a factor affecting the quantity and monomer distribution of alginate from Azotobacter vinelandii ATCC(®) 9046.

    Science.gov (United States)

    Kıvılcımdan Moral, C; Sanin, F D

    2012-03-01

    Alginate is a copolymer of β-D: -mannuronic and α-L: -guluronic acids. Distribution of these monomers in the alginate structure is one of the important characteristics that affect the commercial value of the polymer. In the present work, the effect of agitation speed in the range of 200-700 rpm on alginate production by Azotobacter vinelandii ATCC(®) 9046 was investigated at a dissolved oxygen tension of 5% of air saturation. Experiments were conducted in a fermentor operated in batch mode for 72 h while the production of biomass and alginate, the consumption of substrate and the change in culture broth viscosity and monomer distribution of the polymer were monitored. Results showed that the growth rate of the bacteria increased from 0.165 to 0.239 h(-1) by the increase of mixing speed from 200 to 400 rpm. On the other hand, alginate production was found to be the most efficient at 400 rpm with the highest value of 4.51 g/l achieved at the end of fermentation. The viscosity of culture broth showed similar trends to alginate production. Viscosity was recorded as 24.61 cP at 400 rpm while it was only 4.26 cP at 700 rpm. The MM- and GG-block contents were almost equal in most of the culture times at 400 rpm. On the other hand, GG-blocks dominated at both low and high mixing speeds. Knowing that GG-blocks make rigid and protective gels with divalent cations, due to the higher GG-block content, the gel formation potential is higher at 200 rpm as well at 700 rpm, which might originate from the unfavorable environmental conditions that the bacteria were exposed to. PMID:22009058

  18. Analysis of G-block distributions and their impact on gel properties of in vitro epimerized mannuronan.

    Science.gov (United States)

    Aarstad, Olav; Strand, Berit Løkensgard; Klepp-Andersen, Lise Mari; Skjåk-Bræk, Gudmund

    2013-10-14

    This paper reports a study of the distribution and function of homopolymeric guluronic acid blocks (G-blocks) in enzymatically modified alginate. High molecular weight mannuronan was incubated with one native (AlgE6) and two engineered G-block generating mannuronan C-5 epimerases (AlgE64 and EM1). These samples were found to contain G-blocks with a DP ranging from 20 to approximately 50, lacking the extremely long G-blocks (DP > 100) found in algal alginates. Calcium gels from epimerized materials were highly compressible and exhibited higher syneresis and rupture strength but lower Youngs modulus than gels made from algal polymers of similar G-content. Addition of extremely long G-blocks to the epimerized alginate resulted in decreased syneresis and rupture strength and an increased Young's modulus that can be explained by reinforcement of the cross-linking zones at the cost of length and/or numbers of elastic segments. The presence and impact of these extremely long G-blocks found in natural alginates suggest that alginate gels can be viewed as a nanocomposite material.

  19. Supramolecular liquid-crystal gels formed by polyfluorene-based π-conjugated polymer for switchable anisotropic scattering device.

    Science.gov (United States)

    Chen, Jun-Wei; Huang, Chiu-Chang; Chao, Chih-Yu

    2014-05-14

    To overcome the problem of high driving voltage and low contrast ratio in the switchable scattering device of conventional liquid-crystal (LC) physical gel, a new type of supramolecular LC physical gel has been developed and fabricated through the fibrous self-assembly of the polyfluorene-based π-conjugated polymer, poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), in nematic LC mixture E7. It was found that the rubbed interface between the LC molecules and polyimide layer can induce the LC physical gels to demonstrate fantastic light scattering characteristic. The gels with oriented self-assembled supramolecular structures exhibiting significant anisotropic light scattering in the main-chain direction of the F8BT molecules under an extremely low driving voltage (ca. 2.7 V) are reported for the first time. In addition, the contrast ratio can be reached exceeding 1000. In contrast to conventional LC physical gels, the large reduction of driving voltages of the supramolecular gel provides great possibility for application in various electro-optical devices such as tunable polarizers, transflective displays, and polarized light modulators. PMID:24724859

  20. Three-dimensional dosimetry of TomoTherapy by MRI-based polymer gel technique.

    Science.gov (United States)

    Watanabe, Yoichi; Gopishankar, N

    2010-09-14

    Verification of the dose calculation model and the software used for treatment planning is an important step for accurate radiation delivery in radiation therapy. Using BANG3 polymer gel dosimeter with a 3 Tesla magnetic resonance imaging (MRI) scanner, we examined the accuracy of TomoTherapy treatment planning and radiation delivery. We evaluated one prostate treatment case and found the calculated three-dimensional (3D) dose distributions agree with the measured 3D dose distributions with an exception in the regions where the dose was much smaller (25% or less) than the maximum dose (2.5 Gy). The analysis using the gamma-index (3% dose difference and 3 mm distance-to-agreement) for a volume of 12 cm × 11 cm × 9 cm containing the planning target volume showed that the gamma values were smaller than unity for 53% of the voxels. Our measurement protocol and analysis tools can be easily applied to the evaluation of other newer complex radiation delivery techniques, such as intensity-modulated arc therapy, with a reasonably low financial investment.

  1. Gel polymer electrolytes based on nanofibrous polyacrylonitrile–acrylate for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dul-Sun [Department of Chemical and Biological Engineering, Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of); Woo, Jang Chang [Department of Textile Engineering, Inha University, 100 Inharo, Nam-gu Incheon 402-751 (Korea, Republic of); Youk, Ji Ho, E-mail: youk@inha.ac.kr [Department of Textile Engineering, Inha University, 100 Inharo, Nam-gu Incheon 402-751 (Korea, Republic of); Manuel, James [Department of Chemical and Biological Engineering, Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of); Ahn, Jou-Hyeon, E-mail: jhahn@gnu.ac.kr [Department of Chemical and Biological Engineering, Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of); Department of Materials Engineering and Convergence Technology, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701 (Korea, Republic of)

    2014-10-15

    Graphical abstract: - Highlights: • Nanofibrous polyacrylonitrile–acrylate membranes were prepared by electrospinning. • Trimethylolpropane triacrylate was used as a crosslinking agent of fibers. • The GPE based on PAN–acrylate (1/0.5) showed good electrochemical properties. - Abstract: Nanofibrous membranes for gel polymer electrolytes (GPEs) were prepared by electrospinning a mixture of polyacrylonitrile (PAN) and trimethylolpropane triacrylate (TMPTA) at weight ratios of 1/0.5 and 1/1. TMPTA is used to achieve crosslinking of fibers thereby improving mechanical strength. The average fiber diameters increased with increasing TMPTA concentration and the mechanical strength was also improved due to the enhanced crosslinking of fibers. GPEs based on electrospun membranes were prepared by soaking them in a liquid electrolyte of 1 M LiPF{sub 6} in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v/v). The electrolyte uptake and ionic conductivity of GPEs based on PAN and PAN–acrylate (weight ratio; 1/1 and 1/0.5) were investigated. Ionic conductivity of GPEs based on PAN–acrylate was the highest for PAN/acrylate (1/0.5) due to the proper swelling of fibers and good affinity with liquid electrolyte. Both GPEs based on PAN and PAN–acrylate membranes show good oxidation stability, >5.0 V vs. Li/Li{sup +}. Cells with GPEs based on PAN–acrylate (1/0.5) showed remarkable cycle performance with high initial discharge capacity and low capacity fading.

  2. ZnTe Semiconductor-Polymer Gel Composited Electrolyte for Conversion of Solar Energy

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    Wonchai Promnopas

    2014-01-01

    Full Text Available Nanostructured cubic p-type ZnTe for dye sensitized solar cells (DSSCs was synthesized from 1 : 1 molar ratio of Zn : Te by 600 W and 900 W microwave plasma for 30 min. In this research, their green emissions were detected at the same wavelengths of 563 nm, the energy gap (Eg at 2.24 eV, and three Raman shifts at 205, 410, and 620 cm−1. The nanocomposited electrolyte of quasisolid state ZnO-DSSCs was in correlation with the increase in the JSC, VOC, fill factor (ff, and efficiency (η by increasing the wt% of ZnTe-GPE (gel polymer electrolyte to an optimum value and decreased afterwards. The optimal ZnO-DSSC performance was achieved for 0.20 wt% ZnTe-GPE with the highest photoelectronic energy conversion efficiency at 174.7% with respect to that of the GPE without doping of p-type ZnTe.

  3. Determination of the interaction using FTIR within the composite gel polymer electrolyte

    Science.gov (United States)

    Huang, Yun; Ma, Xiaoyan; Wang, Xu; Liang, Xiao

    2013-01-01

    In the previous research, the gel polymer electrolyte (GPE) which consisted of poly(methyl methacrylate) (PMMA) matrix, propylene carbonate (PC), LiClO4 and OREC (Rectorite modified with dodecyl benzyl dimethyl ammonium chloride), achieved satisfactory properties. In the paper, the interaction between components was quantitatively determined. Characterization of interaction of Cdbnd O in PC and PMMA with Li+ and OH group on OREC surface has been thoroughly examined using FTIR, respectively. The quantitative analysis of FTIR shows that the absorptivity coefficient a of PMMA/LiClO4, PC/LiClO4, PC/OREC and PMMA/OREC is 0.902, 0.113, 0.430 and 0.753, respectively, which means that the Li+ or OH bonded Cdbnd O is more sensitive than the free Cdbnd O in FTIR spectra. The limit value of bonded Cdbnd O equivalent fraction of PMMA/LiClO4, PC/LiClO4, PC/OREC and PMMA/OREC is 17%, 94%, 57% and 20%, respectively, which implies that all the interaction within the components is reversible and the intensity of interaction is ordered as PC/LiClO4, PC/OREC, PMMA/OREC and PMMA/LiClO4.

  4. Femtosecond laser pulse filamentation characterized by polymer gel dosimetry and Fricke dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Meesat, Ridthee; Allard, Jean-Francois; Houde, Daniel; Tremblay, Luc; Khalil, Abdelouahed; Jay-Gerin, Jean-Paul; Lepage, Martin, E-mail: Martin.Lepage@USherbrooke.c [Departement de medecine nucleaire et de radiobiologie, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke (Quebec) J1H 5N4 (Canada)

    2010-11-01

    A femtosecond laser pulse that can generate water radiolysis species was studied in view of its potential medical and biological applications. Intense ultra-short laser pulses can propagate in liquid water, leading to self-focusing and filamentation. Briefly, electrons produced by either multiphoton or tunnel ionization are further accelerated by the electric field of the pulse in an inverse Bremsstrahlung effect. If the electrons acquire enough kinetic energy, they will give rise to a second generation of electrons by impact ionization of other molecules in an avalanche-like process. The geometry and trajectory of femtosecond filaments were captured within a polymer gel dosimeter and imaged by magnetic resonance imaging (MRI) at high resolution. The results revealed that changing pulse duration modifies the penetration of the filament track in the medium. In addition, we used Fricke dosimetry to measure the absorbed dose and dose rate of the femtosecond laser pulse filamentation. A very high dose rate of 5.3 x 10{sup 12} Gy/s was calculated in filaments having a diameter of {approx}600 {mu}m.

  5. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid

    Science.gov (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S.; Ramesh, K.

    2015-12-01

    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10-3 S cm-1 is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm-2, 610 mV and 69.1%, respectively.

  6. Comparison of Energy Dependence of PAGAT Polymer Gel Dosimeter with Electron and Photon Beams using Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    B. Azadbakht

    2012-02-01

    Full Text Available The purpose of this study was to evaluate dependence of PAGAT polymer gel dosimeter 1/T2 on different electron and photon energies for a standard clinically used 60Co therapy unit and an electa linear accelerator.Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2(1/T2 was determined to be 4.5% N,N'-methylen-bis-acrylamide(bis, 4.5% acrylamid(AA, 5% gelatine, 5 mM tetrakis (hydroxymethyl phosphonium chloride (THPC, 0.01 mM hydroquinone (HQ and 86% HPLC(Water. When the preparation of final polymer gel solution is completed, it is transferred into phantoms and allowed to set by storage in a refrigerator at about 4°C. The optimal post-manufacture irradiation and post imaging times were both determined to be 24 h. The sensitivity of PAGAT polymer gel dosimeter with irradiation of photon and electron beams was represented by the slope of calibration curve in the linear region measured for each modality. The response of PAGAT gel with photon and electron beams is very similar in the lower dose region. The R2-dose response was linear up to 30 Gy and the R2-dose response of the PAGAT polymer gel dosimeter is linear between 10 to 30 Gy. In electron beams the R2-dose response for doses less than 3 Gy is not exact, but in photon beams the R2-dose response for doses less than 2Gy is not exact. Dosimeter energy dependence was studied for electron energies of 4, 12 and 18MeV and photon energies of 1.25, 4, 6 and 18 MV. Evaluation of dosimeters were performed on Siemens Symphony, Germany 1.5T Scanner in the head coil. In this study no trend in polymer-gel dosimeter 1/T2 dependence was found on mean energy for electron and photon beams.

  7. Protocol and cell responses in three-dimensional conductive collagen gel scaffolds with conductive polymer nanofibres for tissue regeneration

    OpenAIRE

    Sirivisoot, Sirinrath; Pareta, Rajesh; Harrison, Benjamin S.

    2014-01-01

    It has been established that nerves and skeletal muscles respond and communicate via electrical signals. In regenerative medicine, there is current emphasis on using conductive nanomaterials to enhance electrical conduction through tissue-engineered scaffolds to increase cell differentiation and tissue regeneration. We investigated the role of chemically synthesized polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer nanofibres for conductive gels. To mimic a na...

  8. Tracer diffusion in a polymer gel: simulations of static and dynamic 3D networks using spherical boundary conditions

    Science.gov (United States)

    Kamerlin, Natasha; Elvingson, Christer

    2016-11-01

    We have investigated an alternative to the standard periodic boundary conditions for simulating the diffusion of tracer particles in a polymer gel by performing Brownian dynamics simulations using spherical boundary conditions. The gel network is constructed by randomly distributing tetravalent cross-linking nodes and connecting nearest pairs. The final gel structure is characterised by the radial distribution functions, chain lengths and end-to-end distances, and the pore size distribution. We have looked at the diffusion of tracer particles with a wide range of sizes, diffusing in both static and dynamic networks of two different volume fractions. It is quantitatively shown that the dynamical effect of the network becomes more important in facilitating the diffusional transport for larger particle sizes, and that one obtains a finite diffusion also for particle sizes well above the maximum in the pore size distribution.

  9. Tracer diffusion in a polymer gel: simulations of static and dynamic 3D networks using spherical boundary conditions.

    Science.gov (United States)

    Kamerlin, Natasha; Elvingson, Christer

    2016-11-30

    We have investigated an alternative to the standard periodic boundary conditions for simulating the diffusion of tracer particles in a polymer gel by performing Brownian dynamics simulations using spherical boundary conditions. The gel network is constructed by randomly distributing tetravalent cross-linking nodes and connecting nearest pairs. The final gel structure is characterised by the radial distribution functions, chain lengths and end-to-end distances, and the pore size distribution. We have looked at the diffusion of tracer particles with a wide range of sizes, diffusing in both static and dynamic networks of two different volume fractions. It is quantitatively shown that the dynamical effect of the network becomes more important in facilitating the diffusional transport for larger particle sizes, and that one obtains a finite diffusion also for particle sizes well above the maximum in the pore size distribution. PMID:27662260

  10. Investigation of the Spatial Resolution of MR-Based Polymer Gel Dosimetry versus Film Densitometry using Dose Modulation Transfer Function

    Directory of Open Access Journals (Sweden)

    Reza Moghadam-Drodkhani

    2011-03-01

    Full Text Available Introduction: The conventional methods of dosimetry are not capable of dosimetry in such a small volume of less than one cubic millimeter. Although the polymer gel dosimetry method based on magnetic resonance imaging (MRI could achieve three dimensional dosimetry with high resolution, a spatial resolution evaluation based on gel dose modulation transfer function has not been investigated yet. Therefore, in this study, the spatial resolution of two systems of film densitometry and polymer gel dosimetry based on MRI has been evaluated by using the dose modulation transfer function (DMTF.   Material and Methods: Kodak therapy verification films and MAGICA polymer gel samples were positioned below a brass absorption grid with different periodic slices (a/2= 280, 525, 1125 μm, which was placed in a water bath container to avoid regions of dose build-up just below the absorption grid and then irradiated with Cobalt-60 photons on a Theratron external-beam treatment unit. Dose variation under the brass grid was determined using a calibration curve, while transverse relaxation time (T2 as the selective parameter in a dose image based on multiple echo MRI with 1.5 Tesla GE Signa Echo Speed system (FOV=10 cm, matrix size=512 ×512, pixel size =0.199×0.199 mm2, TE = 20, 40, 60, 80 ms, TR=4200 ms, NEX = 4, slice thickness=2 mm, gap=1 mm was calculated. DMTF from the modulation depths of T2 and variation in film optical density after calibration would be achieved. The results of polymer gel were compared with film. Results: After deriving the dose distribution profile under the absorption grid, minima and maxima at the smallest period of a = 560 μm could scarcely be resolved, but the modulations due to a=2250 μm and a = 1050 μm grids could be discerned. The modulation depth for a=2250 μm grid was set to 100% and the other modulations were subsequently referred to this maximum modulation. For film densitometry at a = 1050 μm, the modulation depth was

  11. Scaling of the kinetics of slow aggregation and gel formation for a fluorinated polymer colloid.

    Science.gov (United States)

    Sandkühler, Peter; Sefcik, Jan; Morbidelli, Massimo

    2005-03-01

    The aggregation and gelation kinetics in moderately concentrated (0.004 polymer particles has been studied. The aggregation was adjusted to proceed slowly enough to allow a convenient characterization of the kinetics through static and dynamic light scattering on quenched and diluted samples. A population balance model based on second-order aggregation rates is developed to compute the time evolution of the cluster mass distribution, from which we calculate the values of the average radii and structure factor measured by light scattering, so as to allow a direct comparison between measured and calculated quantities. The model suggests the introduction of a dimensionless time which allows the scaling of all the aggregation data on unique master curves defined by only two parameters: the exponent of the power-law aggregation kernel, lambda, and the aggregate fractal dimension, d(f). The predicted master curves were observed experimentally, which confirms the validity of the aggregation model and allows the unique determination of the kinetic and structural parameters of the aggregation process. The cluster growth behavior, although significantly slower than DLCA, shows power-law kinetics rather than the exponential one typical of RLCA and the cluster structure is characterized by an unexpectedly small fractal dimension, d(f) = 1.7. The occurrence of gelation has been characterized using small amplitude oscillatory shearing to monitor the time evolution of the elastic modulus. It is found that also these curves, together with the gel time value, scale with the stability ratio of primary particles for a given solid volume fraction. We further use the model to calculate the cumulative occupied volume fraction of the growing aggregates and quantify in this way the increasing space filling, which is solid volume fraction dependent. The experimentally determined dimensionless gel times, which are also solid volume

  12. Polymer gels impregnated with gold nanoparticles implemented for measurements of radiation dose enhancement in synchrotron and conventional radiotherapy type beams

    International Nuclear Information System (INIS)

    Normoxic type polyacrylamide gel (nPAG) dosimeters are established for dose quantification in three-dimensions for radiotherapy and hence represent an adequate dosimeter for quantification of the dose variation due to the existence of the gold nanoparticles (AuNPs) in the target during irradiation. This work compared the degree of polymerisation in gel doped with nanoparticles (nPAG–AuNP) with control gel samples when irradiated by various sources. Samples were irradiated with a synchrotron radiation source of mean energy 125 keV, 80 kV X-ray beams from superficial therapy machine (SXRT), 6 MV X-rays and 6 MeV electron beams from linear accelerator. Analysis of the dose–response relation was used to determine a dose enhancement factor (DEF) of 1.76 ± 0.34 and 1.64 ± 0.44 obtained for samples irradiated with kilovoltage X-rays energy from synchrotron source and SXRT respectively. Similarly, including AuNPs in gel results in a DEF of approximately 1.37 ± 0.35 when irradiated by an electron beam and 1.14 ± 0.28 for high energy X-ray beams. The results demonstrate the use of AuNPs embedded in polymer gels for measuring the enhancement of radiation caused by metallic nanoparticles.

  13. A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

    Directory of Open Access Journals (Sweden)

    Cheng-Ting Shih

    Full Text Available Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM images. The modified N-isopropyl-acrylamide (NIPAM gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM. The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2 value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

  14. Biocompatibility and Degradation of Polyvinyl Alcohol Gel and Sodium Alginate Geln in vivo%PVA水凝胶、海藻酸钠凝胶与羊椎骨支架粘合植入动物体内观察

    Institute of Scientific and Technical Information of China (English)

    马文渊; 何惠宇; 杨楠; 刘勤; 王媛

    2013-01-01

    Objective:To lay foundation for the study of 3D printing technology to construct tissue engineered bone through investigating in vivo biocompatibility and degradation rate of polyvinyl alcohol gel and sodium alginate gel.Methods:The experimental samples were divided into three groups,the sheep vertebrae scaffold materials as control group,polyvinyl alcohol gel-sheep vertebrae scaffold as experimental group 1,sodium alginate gel-sheep vertebrae scaffold as experimental group 2.The three kinds of materials were implanted into nude mice,which was killed in the first four weeks and eight weeks after surgery and then observed the HE dying.Results:Specimens showed a large number of fibrous connective tissue and skin blood capillary in two experimental groups and the control group materials 4 weeks after the surgery.And connective tissue hyperplasia and inflammatory cells infiltration were found around the implant materials.The edge of control group was shaped like a burr.The colloidal absorption was not obvious in the two experimental groups and loose fibre capsule walls were formed around the scaffold materials.Eight weeks after surgery,specimens showed burr edges and inflammatory cells infiltrated in the scaffold materials group.Skin inflammatory cells obviously increased,no obvious dilation of capillaries and osteoclast adhere to scaffold materials in experimental group 1.The experimental group 2 and control group materials surrounding tissue inflammation reaction decreased,a small amount of neutrophils and plasma cell infiltrated.Experimental group 2 showed that osteoclast adhesion and a small proportion of the gel colloidal degraded.And there was a burr edge in scaffold bone materials.Conclusion:Short-term absorption was seen in the control group and sodium alginate gel group but not in the polyvinyl alcohol gel group.%目的:研究聚乙烯醇水凝胶、海藻酸钠凝胶在生物体内生物相容性及降解速率,为三维快速打印技术构建组织工程

  15. EFFICIENT FORMULATION AND CHARACTERIZATION OF FLURBIPROFEN TRANSDERMAL GEL USING WATER SOLUBLE POLYACRYLAMIDE POLYMER

    Directory of Open Access Journals (Sweden)

    Jeevaprakash Ganapathi*1 and Dheivanai Jeevaprakash 2

    2012-06-01

    Full Text Available High molecular weights water soluble homopolymer type of acrylamide was reported to obtain very high viscosity in low concentration, transparency, film forming properties and useful in formation of transdermal gel. The flurbiprofen gels were prepared by using different concentration of polyacrylamide for topical drug delivery with an aim to gradually increase transparency and spreadability. These preparations were further compared with marketed known flurbiprofen gel. Spreadability and consistency of polyacrylamide gel containing flurbiprofen gel (S9 were 6.5g.cm/sec and 5mm as compared to 5.5g.cm/sec and 10mm respectively of known marketed gel, indicating good spreadability nature and consistency of the prepared gel (S9. The transparency nature of prepared batch (S9 was good as compared to the known marketed gel. The percent drug release was 97.85 and 98.84 from S9 and known marketed gel respectively. No irritation was felt in the skin irritation test. Stability studies conducted under accelerated condition was shown satisfactory results. It can be concluded that polyacrylamide gel containing flurbiprofen gel showed good consistency, spreadability, homogeneity and stability and had wider prospect for topical preparations.

  16. Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels

    International Nuclear Information System (INIS)

    Purpose: This work proposes and implements an experimental methodology, based on polymer gels, for assessing the total geometric uncertainty and characterizing its contributors in Gamma Knife (GK) radiosurgery. Methods: A treatment plan consisting of 26, 4-mm GK single shot dose distributions, covering an extended region of the Leksell stereotactic space, was prepared and delivered to a polymer gel filled polymethyl methacrylate (PMMA) head phantom (16 cm diameter) used to accurately reproduce every link in the GK treatment chain. The center of each shot served as a “control point” in the assessment of the GK total geometric uncertainty, which depends on (a) the spatial dose delivery uncertainty of the PERFEXION GK unit used in this work, (b) the spatial distortions inherent in MR images commonly used for target delineation, and (c) the geometric uncertainty contributor associated with the image registration procedure performed by the Leksell GammaPlan (LGP) treatment planning system (TPS), in the case that registration is directly based on the apparent fiducial locations depicted in each MR image by the N-shaped rods on the Leksell localization box. The irradiated phantom was MR imaged at 1.5 T employing a T2-weighted pulse sequence. Four image series were acquired by alternating the frequency encoding axis and reversing the read gradient polarity, thus allowing the characterization of the MR-related spatial distortions. Results: MR spatial distortions stemming from main field (B0) inhomogeneity as well as from susceptibility and chemical shift phenomena (also known as sequence dependent distortions) were found to be of the order of 0.5 mm, while those owing to gradient nonlinearities (also known as sequence independent distortions) were found to increase with distance from the MR scanner isocenter extending up to 0.47 mm at an Euclidean distance of 69.6 mm. Regarding the LGP image registration procedure, the corresponding average contribution to the total

  17. Three dimensional visualization and measurement of conformal dose distributions using magnetic resonance imaging of BANG polymer gel dosimeters

    International Nuclear Information System (INIS)

    Purpose/objective: The measurement of complex dose distributions (those created by irradiation through multiple beams or multiple source dwell positions) requires a dosimeter that can integrate the dose during a complete treatment. Integrating dosimeter devices generally are capable of measuring only dose at a point (ion chamber, diode, TLD) or in a plane (film). With increasing use of conformal dose distributions, requiring shaped, noncoplanar beams, there will be an increased requirement for a dosimeter that can record and display a 3-D dose distribution. The use of a 3-D dosimeter will be required to confirm the accuracy of treatment plans produced by the current generation of 3-D treatment planning computers. Materials and methods: We have previously described the use of a Fricke-infused gel and magnetic resonance imaging (MRI) to demonstrate the localization of stereotactic beams. The recently developed BANG polymer gel dosimetry system (MGS Research, Inc., Guilford, CT), based on radiation-induced chain polymerization of acrylic monomers dispersed in a tissue-equivalent gel, surpasses the Fricke-gel method by providing accurate, quantitative dose distribution data that do not deteriorate with time. The improved BANG2 formulation contains 3% N, N'-methylene-bisacrylamide, 3% acrylic acid, 1% sodium hydroxide, 5% gelatin, and 88% water, where all percentages are by weight. The gel was poured into volumetric flasks, of dimensions comparable to a human head. The gels were irradiated with complex beam arrangements, similar to those used for conformal radiation therapy. Images of the gels were acquired using a Siemens 1.5T imager and a Hahn spin-echo pulse sequence (90 deg. -τ-180 deg. -τ-acquire, for different values of τ). The images were transferred via network to a Macintosh computer for which a data analysis and display program was written. The program calculates R2 maps on the basis of multiple TE images, using a monoexponential non-linear least squares

  18. Electric double-layer capacitors with tea waste derived activated carbon electrodes and plastic crystal based flexible gel polymer electrolytes

    Science.gov (United States)

    Suleman, M.; Deraman, M.; Othman, M. A. R.; Omar, R.; Hashim, M. A.; Basri, N. H.; Nor, N. S. M.; Dolah, B. N. M.; Hanappi, M. F. Y. M.; Hamdan, E.; Sazali, N. E. S.; Tajuddin, N. S. M.; Jasni, M. R. M.

    2016-08-01

    We report a novel configuration of symmetrical electric double-layer capacitors (EDLCs) comprising a plastic crystalline succinonitrile (SN) based flexible polymer gel electrolyte, incorporated with sodium trifluoromethane sulfonate (NaTf) immobilised in a host polymer poly (vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP). The cost-effective activated carbon powder possessing a specific surface area (SSA) of ~ 1700 m2g-1 containing a large proportion of meso-porosity has been derived from tea waste to use as supercapacitor electrodes. The high ionic conductivity (~3.6×10-3 S cm-1 at room temperature) and good electrochemical stability render the gel polymer electrolyte film a suitable candidate for the fabrication of EDLCs. The performance of the EDLCs has been tested by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge-discharge studies. The performance of the EDLC cell is found to be promising in terms of high values of specific capacitance (~270 F g-1), specific energy (~ 36 Wh kg-1), and power density (~ 33 kW kg-1).

  19. Preparation of organic/inorganic composite membranes using two types of polymer matrix via a sol-gel process

    Science.gov (United States)

    Park, Seung-Hee; Park, Jin-Soo; Yim, Sung-Dae; Park, Seok-Hee; Lee, Young-Moo; Kim, Chang-Soo

    Organic/inorganic composite membranes were prepared using two different polymers. BPO 4 particles were introduced into polymers via an in situ sol-gel process. Pre-/post-sulfonated polymers were used to prepare composite membranes as matrix. Pre-sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymer was synthesized via nucleophilic aromatic substitution. Degree of sulfonation was adjusted by the percentage of sulfonated monomer. Post-sulfonated poly(ether ether ketone) (SPEEK) was prepared using concentrated sulfuric acid as sulfonation agent. The membranes were characterized in terms of the ion-exchange capacity (IEC), proton conductivity, water uptake, AFM, SEM and their thermal properties. The SPAEK-6F plain membranes showed higher proton conductivity than that of the SPEEK plain membranes at similar water uptake or IEC due to their structural difference. SEM images of the composite membranes showed that the BPO 4 particles were homogenously dispersed in the polymer matrices and BPO 4 particle size was greatly influenced by polymer matrix. The SPAEK-6F/BPO 4 composite membranes had much smaller BPO 4 particle size than the SPEEK/BPO 4 composite membranes due to well dispersion of BPO 4 sol-like particulates in SPAEK-6F polymer solutions forming more hydrophobic/hydrophilic nanophase than SPEEK polymer solutions. The latter containing a few micrometer-scale BPO 4 particles showed higher proton conductivity than the former containing hundreds nanometer-scale BPO 4 particles at similar water uptake due to the increase in freezable water and effect of particle size.

  20. Technical Note: Preliminary investigations into the use of a functionalised polymer to reduce diffusion in Fricke gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S. T., E-mail: s164.smith@qut.edu.au; Masters, K.-S.; Hosokawa, K.; Blinco, J. P.; Trapp, J. V. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000 (Australia); Crowe, S. B. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, Australia and Cancer Care Services, Royal Brisbane and Women’s Hospital, Brisbane 4006 (Australia); Kairn, T. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, Australia and Genesis Cancer Care Queensland, Brisbane 4066 (Australia)

    2015-12-15

    Purpose: A modification of the existing PVA-FX hydrogel has been made to investigate the use of a functionalised polymer in a Fricke gel dosimetry system to decrease Fe{sup 3+} diffusion. Methods: The chelating agent, xylenol orange, was chemically bonded to the gelling agent, polyvinyl alcohol (PVA) to create xylenol orange functionalised PVA (XO-PVA). A gel was created from the XO-PVA (20% w/v) with ferrous sulfate (0.4 mM) and sulfuric acid (50 mM). Results: This resulted in an optical density dose sensitivity of 0.014 Gy{sup −1}, an auto-oxidation rate of 0.0005 h{sup −1}, and a diffusion rate of 0.129 mm{sup 2} h{sup −1}; an 8% reduction compared to the original PVA-FX gel, which in practical terms adds approximately 1 h to the time span between irradiation and accurate read-out. Conclusions: Because this initial method of chemically bonding xylenol orange to polyvinyl alcohol has inherently low conversion, the improvement on existing gel systems is minimal when compared to the drawbacks. More efficient methods of functionalising polyvinyl alcohol with xylenol orange must be developed for this system to gain clinical relevance.

  1. Direct Evidence for Percolation of Immobilized Polymer Layer around Nanoparticles Accounting for Sol-Gel Transition in Fumed Silica Dispersions.

    Science.gov (United States)

    Zheng, Zhong; Song, Yihu; Yang, Ruiquan; Zheng, Qiang

    2015-12-22

    Immobilized polymer fractions have been claimed to be of vital importance for sol-gel transitions generally observed in nanoparticle dispersions but remain a matter of debate regarding mechanism and difficulty for prediction. Here we investigate the immobilized layer structures of trifunctionality polyether polyol (PPG) near the surfaces of hydrophilic and hydrophobic fumed silica (FS) nanoparticles to reveal the role of surface chemistry on the molecular dynamics and sol-gel transitions of the dispersions. Using modulated differential scanning calorimetry, we measure the specific heat capacity during glass transition and the enthalpy during cold-crystallization. Comparing with hydrophobic FS that forms a fully immobilized (glassy) layer, we find that hydrophilic FS immobilizes more PPG, forming a partially immobilized outer layer being unable to crystallize next to the inner glassy layer. By correlating the thickness of the glassy layer with half of the minimum spacing between nanoparticles, we directly evidence the percolation of this layer along the nearest neighbor nanoparticles responsible for the sol-gel transition. Using effective volume fraction including the glassy layer, we successfully construct master curves of relative viscosity of both hydrophilic and hydrophobic FS dispersions, pointing to a common sol-gel transition mechanism mediated by the surface chemistry.

  2. Does nitrogen gas bubbled through a low density polymer gel dosimeter solution affect the polymerization process?

    Directory of Open Access Journals (Sweden)

    Daryoush Shahbazi-Gahrouei

    2015-01-01

    Conclusion: It appeared that reactions between gelatin-free radicals and monomers, due to an increase in the gel temperature during rotation in the household mixer, led to a higher R 2 -background response. In the second type of gel, it seemed that the collapse of the nitrogen bubbles was the main factor that affected the R 2 -responses.

  3. Preliminary study of MAGAT polymer gel dosimetry for boron-neutron capture therapy

    Science.gov (United States)

    Hayashi, Shin-ichiro; Sakurai, Yoshinori; Uchida, Ryohei; Suzuki, Minoru; Usui, Shuji; Tominaga, Takahiro

    2015-01-01

    MAGAT gel dosimeter with boron is irradiated in Heavy Water Neutron Irradiation Facility (HWNIF) of Kyoto University Research Reactor (KUR). The cylindrical gel phantoms are exposed to neutron beams of three different energy spectra (thermal neutron rich, epithermal and fast neutron rich and the mixed modes) in air. Preliminary results corresponding to depth-dose responses are obtained as the transverse relaxation rate (R2=1/T2) from magnetic resonance imaging data. As the results MAGAT gel dosimeter has the higher sensitivity on thermal neutron than on epi-thermal and fast neutron, and the gel with boron showed an enhancement and a change in the depth-R2 response explicitly. From these results, it is suggested that MAGAT gel dosimeter can be an effective tool in BNCT dosimetry.

  4. Quasi-solid-state nanocrystalline TiO2 solar cells using gel network polymer electrolytes based on polysiloxanes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A quasi-solid-state dye-sensitized nanocrystalline porous TiO2 film solar cell was fabricated using a novel gel network polymer electrolyte based on polysiloxanes with both polyethylene oxide internal plasticized side chains and quaternary ammonium groups. The cell exhibited better photoelectrical conversion performance under 60 mW/cm2 irradiation. The short photocurrent (Isc) of 5.0 mA/cm2 and open voltage (Voc) of 0.68 V were achieved, and the energy conversion efficiency (η) and fill factor (ff) were 3.4% and 0.60, respectively.

  5. Artificial Neural Network and Response Surface Methodology Modeling in Ionic Conductivity Predictions of Phthaloylchitosan-Based Gel Polymer Electrolyte

    Directory of Open Access Journals (Sweden)

    Ahmad Danial Azzahari

    2016-01-01

    Full Text Available A gel polymer electrolyte system based on phthaloylchitosan was prepared. The effects of process variables, such as lithium iodide, caesium iodide, and 1-butyl-3-methylimidazolium iodide were investigated using a distance-based ternary mixture experimental design. A comparative approach was made between response surface methodology (RSM and artificial neural network (ANN to predict the ionic conductivity. The predictive capabilities of the two methodologies were compared in terms of coefficient of determination R2 based on the validation data set. It was shown that the developed ANN model had better predictive outcome as compared to the RSM model.

  6. A composite membrane based on a biocompatible cellulose as a host of gel polymer electrolyte for lithium ion batteries

    Science.gov (United States)

    Xiao, S. Y.; Yang, Y. Q.; Li, M. X.; Wang, F. X.; Chang, Z.; Wu, Y. P.; Liu, X.

    2014-12-01

    A composite polymer membrane is prepared by coating poly(vinylidene fluoride) (PVDF) on the surface of a membrane based on methyl cellulose (MC) which is environmentally friendly and cheap. Its characteristics are investigated by scanning electron microscopy, FT-IR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The outer PVDF layers are porous which results in high electrolyte uptake and the lithium ion transference number is much larger than that of the pure MC. Moreover, the cell based on Li//LiFePO4 delivers high discharge capacity and good rate behavior in the range of 4.2-2.5 V when the composite membrane is used as the separator and the host of a gel polymer electrolyte, lithium as the counter and reference electrode, and LiFePO4 as cathode. The obtained results suggest that this unique composite membrane shows great attraction in the lithium ion batteries with high safety and low cost.

  7. Colloidal interactions of inorganic nanoparticles grafted with zwitterionic polymer brushes and gels by surface-mediated seeded polymerization.

    Science.gov (United States)

    An, Soyoun; Choi, Sang Koo; Cho, Jang Woo; Kim, Hyun Tae; Kim, Jin Woong

    2014-08-01

    A robust and straightforward approach is introduced to synthesize inorganic nanoparticles chemically grafted with a zwitterionic poly(2-methacryroyloxyethylphosphorylcholine) (PMPC) thin layers. The synthesis method is based on the surface-mediated seeded polymerization. In order to observe how the polymer chain architectures affect colloidal interactions, the zinc oxide nanoparticles are grafted with linear brushes and with a thin hydrogel layer, respectively. The thickness of PMPC shell layers spans a few nanometers. The studies on suspension rheology for the nanoparticles show that the nanoparticles with PMPC brushes show the stronger repulsive force than those with the PMPC gel shell due to the entropic stabilization. When the shear force is applied to the Pickering emulsion produced by assembly of the nanoparticles, it is noticeable that the presence of PMPC brushes on the particles rather enhances the drop-to-drop attraction, which presumably stems from the entanglement of polymer chains between the contacted interfacial planes of the emulsion droplets during shearing.

  8. Synergetic effect of green tea on polymer gel dosimeter and determination of optimal wavelength to choose light source for optical computed tomography

    Directory of Open Access Journals (Sweden)

    Sathiya Raj

    2016-03-01

    Full Text Available Purpose: The ultimate aim of this study is to observe the effect of Green tea as a co-antioxidant in PAGAT gel dosimeter and evaluate the appropriate light source for scanning the PAGAT and NIPAM polymer gel.Methods: Both PAGAT (Poly Acrylamide Gelatin Tetrakis hydroxyl phosphonium chloride and NIPAM (N-Isopropyl acrylamide gel were prepared in normoxic condition. The green tea extract (GTE was prepared and tested only on PAGAT. Co-60 teletherapy machine has been used for irradiation purpose, and the gel samples were scanned using UV-Visible spectrophotometer. Water equivalency of the gel has been tested in terms of their electron density, effective atomic number and Ratio of oxygen and hydrogen (O/H. We have used NIST XCOM database to test the water equivalency.Results: In this study we found that the GTE added to the gel do not respond to the given doses. By adding sugar we can enhance the sensitivity of the gel. Further investigations are required to use Green tea as a co antioxidant concentration of THPC (Tetrakis hydroxymethyl phosphonium chloride. The optimal wavelength with different region for scanning the PAGAT is 450 to 480 nm (Blue region, for NIPAM it is 540 nm and 570 nm (Green and yellow region. The PAGAT and NIPAM showed better sensitivity at 510 nm. Both gels have their effective atomic number closer to water (NIPAM-7.2, PAGAT-7.379.Conclusion: As per our results, we concluded that GTE alone is not an effective co-antioxidant for polymer gels. When the GTE is combined with sugar and THPC, it protects the gel from pre-polymerization. This study strongly suggests that the blue light is an optimal source for scanning the PAGAT and green to yellow light for NIPAM gel. Though both gels were considered as water equivalent, the PAGAT is equivalent to water and the temporal stability of this gel is higher than NIPAM.

  9. Organic-inorganic Polymer Nano-hybrids Based on Sol-gel Reaction

    Institute of Scientific and Technical Information of China (English)

    Yoshiki; Chujo

    2007-01-01

    1 Results Nano-ordered composite materials consisting of organic polymers and inorganic materials have been attracting attention for the purpose of the creation of high-performance or high-functional polymeric materials. Especially,the word of "polymer hybrid" claims the blends of organic and inorganic components at nano-level dispersion. By using this idea,an enhancement of mechanical strength of organic polymers with silica particles is possible.High transparency of this material is another important ...

  10. FORMULATION AND EVALUATION OF TOPICAL DICLOFENAC SODIUM GEL USING DIFFERENT GELLING AGENT

    Directory of Open Access Journals (Sweden)

    Y. S. TANWAR, AMIT KUMAR JAIN

    2013-09-01

    Full Text Available The present research has been undertaken with the aim to develop a topical gel formulation of Diclofenac sodium usingdifferent gelling agent carbopol, Na CMC, HPMC (K4M and sodium alginate in different concentration, which wouldattenuate the gastrointestinal relater toxicities associated with oral administration. They were evaluated for physicochemicalproperties such as homogeneity, grittiness, viscosity, pH, Spreadability, drug content, skin irritancy, in vitro drug release,stability studies. The in vitro drug release rate of gel was evaluated using Franz diffusion cell containing cellophanemembrane with phosphate buffer pH 6.8 as the receptor medium. Studies showed that drug release was decrease withincrease in gelling agent concentration because polymer concentration increases, viscosity increases. Drug was absorbedfrom site of application as long as it remains in higher concentration gelling agent in solution form.Keywords: Diclofenac Sodium, carbopol, hydroxyl propyl methyl cellulose, sodium alginate anti‐inflammatory activity.

  11. Effect of Sodium Alginate on Rheological Properties and Gel Properties of Three Kinds of Flour with Different Gluten Content%海藻酸钠对3种不同面筋含量面粉流变学性质和凝胶性质的影响

    Institute of Scientific and Technical Information of China (English)

    王慧云; 赵阳; 陈海华; 王雨生

    2014-01-01

    采用动态流变仪、物性测试仪研究了不同添加量的海藻酸钠对3种面筋含量的面粉流变学性质、凝胶性质的影响。结果表明,海藻酸钠影响3种面粉的流变性质和凝胶性质。随着海藻酸钠质量分数的增加,3种面粉的表观黏度、稠度系数逐渐增加,流动指数基本不变。添加4%的海藻酸钠后,与中筋粉、高筋粉相比,低筋粉的贮能模量G′最高,损耗角 tanδ最低,较易形成弹性凝胶。添加海藻酸钠能促进3种面粉的老化,减弱其蠕变恢复特性。添加4%的海藻酸钠,撤去应力后中筋粉的应变下降幅度最大,约下降67.24%;且随着面筋含量的增加,面粉的凝胶硬度和弹性逐渐增加。%Effect of sodium alginate of different addition on rheological properties and gelling properties of three kinds of flour with different gluten content were analysed by dynamic rheometer and texture analy-ser.The results showed that rheological properties and gelling properties of three kinds of flour were af-fected by sodium alginate.With addition of sodium alginate increasing,apparent viscosity and consistency coefficient were increased gradually,while flow index was not significantly changed.Compared with middle gluten flour and high gluten flour,storage modulus of weak gluten flour was the highest and tanδwas the lowest when addition of sodium alginate was 4%,therefore,the weak gluten flour was the easiest to form viscoelastic gel.Retrogradation of three kinds of wheat flour was promoted and creep-recovery was re-duced by sodium alginate.With addition of 4% sodium alginate,the stress of middle-gluten-content flour was decreased the largest by 67.24%,while gel hardness and springness also were increased with the gluten content increasing.

  12. 海藻酸钠对3种不同面筋含量面粉流变学性质和凝胶性质的影响%Effect of Sodium Alginate on Rheological Properties and Gel Properties of Three Kinds of Flour with Different Gluten Content

    Institute of Scientific and Technical Information of China (English)

    王慧云; 赵阳; 陈海华; 王雨生

    2014-01-01

    采用动态流变仪、物性测试仪研究了不同添加量的海藻酸钠对3种面筋含量的面粉流变学性质、凝胶性质的影响。结果表明,海藻酸钠影响3种面粉的流变性质和凝胶性质。随着海藻酸钠质量分数的增加,3种面粉的表观黏度、稠度系数逐渐增加,流动指数基本不变。添加4%的海藻酸钠后,与中筋粉、高筋粉相比,低筋粉的贮能模量G′最高,损耗角 tanδ最低,较易形成弹性凝胶。添加海藻酸钠能促进3种面粉的老化,减弱其蠕变恢复特性。添加4%的海藻酸钠,撤去应力后中筋粉的应变下降幅度最大,约下降67.24%;且随着面筋含量的增加,面粉的凝胶硬度和弹性逐渐增加。%Effect of sodium alginate of different addition on rheological properties and gelling properties of three kinds of flour with different gluten content were analysed by dynamic rheometer and texture analy-ser.The results showed that rheological properties and gelling properties of three kinds of flour were af-fected by sodium alginate.With addition of sodium alginate increasing,apparent viscosity and consistency coefficient were increased gradually,while flow index was not significantly changed.Compared with middle gluten flour and high gluten flour,storage modulus of weak gluten flour was the highest and tanδwas the lowest when addition of sodium alginate was 4%,therefore,the weak gluten flour was the easiest to form viscoelastic gel.Retrogradation of three kinds of wheat flour was promoted and creep-recovery was re-duced by sodium alginate.With addition of 4% sodium alginate,the stress of middle-gluten-content flour was decreased the largest by 67.24%,while gel hardness and springness also were increased with the gluten content increasing.

  13. A novel stability-enhanced lithium-oxygen battery with cellulose-based composite polymer gel as the electrolyte

    International Nuclear Information System (INIS)

    Highlights: • A novel cellulose-based composite polymer gel electrolyte (PGE) membrane is prepared. • PGE exhibits excellent ionic conductivity and electrochemical stability. • PEG reduces the penetration of oxygen to lithium anode and electrolyte loss. • Non-aqueous Li/O2 battery employing PGE membrane displays good cyclic stability. - Abstract: A novel lithium-oxygen (Li-O2) battery with a polymer gel electrolyte (PGE) membrane is successfully prepared. The membrane is a blend of cellulose acetate (CA) and poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) and is fabricated using a solution casting technique followed by impregnation with lithium bis(trifluoromethane sulfonimide) (LiTFSI) solution. We demonstrate that the PGE membrane has good electrolyte uptake and shows high ionic conductivity as well as excellent thermal and electrochemical stability. A Li-O2 battery containing our PGE as the electrolyte and separator exhibits good rate capability and enhanced cycling capacity retention compared to a battery using commercial liquid electrolyte and a polyethylene (PE) separator under the same conditions. We attribute this enhanced performance to the PGE, which maybe restrain the diffusion of oxygen from the air cathode to the Li metal anode. This study may prove valuable for resolving the problem of poor cycling stability in Li-O2 batteries caused by oxygen diffusion from cathode to anode

  14. SYNTHESIS AND OPTICAL PROPERTIES OF A NOVEL ORGANIC/INORGANIC HYBRID NONLINEAR OPTICAL POLYMER VIA SOL-GEL PROCESS

    Institute of Scientific and Technical Information of China (English)

    Hong-xia Xi; Zhong Li; Zhao-xi Liang

    2001-01-01

    A new organic/inorganic hybrid nonlinear optical (NLO) material was developed by the sol-gel process of an alkoxysilane dye with tetraethoxysilane. A NLO moiety based on 4-nitro-4′-hydroxy azobenzene was covalently bonded to the triethoxysilane derivative, i.e. γ-isocyanatopropyl triethoxysilane. The preparation process and properties of the sol-gel derived NLO polymer were studied and characterized by SEM, FTIR, 1H-NMR, UV-Vis, DSC and second harmonic generation (SHG) measurement. The results indicated that the chemical bonding of the chromophores to the inorganic SiO2 networks induces Iow dipole alignment relaxation and preferable orientational stability. The SHG measurements also showed that the bonded polymer film containing 75 wt% of the akoxysilane dye has a high electro-optic coefficient (r33) of7. 1 pm/V at 1.1 μm wavelength, and exhibit good SHG stability, the r33 values can maintain about 92.7% of its initial value at room temperature for 90 days, and can maintain about 59.3% at 100℃ for 300 min.``

  15. Study of hafnium (IV) oxide nanoparticles synthesized by polymerized complex and polymer precursor derived sol-gel methods

    KAUST Repository

    Ramos-González, R.

    2010-03-01

    This work reports the preparation and characterization of hafnium (IV) oxide (HfO2) nanoparticles grown by derived sol-gel routes that involves the formation of an organic polymeric network. A comparison between polymerized complex (PC) and polymer precursor (PP) methods is presented. For the PC method, citric acid (CA) and ethylene glycol (EG) are used as the chelating and polymerizable reagents, respectively. In the case of PP method, poly(acrylic acid) (PAA) is used as the chelating reagent. In both cases, different precursor gels were prepared and the hafnium (IV) chloride (HfCl4) molar ratio was varied from 0.1 to 1.0 for the PC method and from 0.05 to 0.5 for the PP method. In order to obtain the nanoparticles, the precursors were heat treated at 500 and 800 °C. The thermal characterization of the precursor gels was carried out by thermogravimetric analysis (TGA) and the structural and morphological characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the samples obtained by both methods shows the formation of HfO2 at 500 °C with monoclinic crystalline phase. The PC method exhibited also the cubic phase. Finally, the HfO2 nanoparticles size (4 to 11 nm) was determined by TEM and XRD patterns. © (2010) Trans Tech Publications.

  16. Thermogelling Bioadhesive Scaffolds for Intervertebral Disc Tissue Engineering: Preliminary In Vitro Comparison of Aldehyde-Based Versus Alginate Microparticle-Mediated Adhesion

    Science.gov (United States)

    Wiltsey, C.; Christiani, T.; Williams, J.; Scaramazza, J.; Van Sciver, C.; Toomer, K.; Sheehan, J.; Branda, A.; Nitzl, A.; England, E.; Kadlowec, J.; Iftode, C.; Vernengo, J.

    2015-01-01

    Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or “end-capping”, the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase two-fold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration. PMID:25641647

  17. Thermogelling bioadhesive scaffolds for intervertebral disk tissue engineering: preliminary in vitro comparison of aldehyde-based versus alginate microparticle-mediated adhesion.

    Science.gov (United States)

    Wiltsey, C; Christiani, T; Williams, J; Scaramazza, J; Van Sciver, C; Toomer, K; Sheehan, J; Branda, A; Nitzl, A; England, E; Kadlowec, J; Iftode, C; Vernengo, J

    2015-04-01

    Tissue engineering of certain load-bearing parts of the body can be dependent on scaffold adhesion or integration with the surrounding tissue to prevent dislocation. One such area is the regeneration of the intervertebral disc (IVD). In this work, poly(N-isopropylacrylamide) (PNIPAAm) was grafted with chondroitin sulfate (CS) (PNIPAAm-g-CS) and blended with aldehyde-modified CS to generate an injectable polymer that can form covalent bonds with tissue upon contact. However, the presence of the reactive aldehyde groups can compromise the viability of encapsulated cells. Thus, liposomes were encapsulated in the blend, designed to deliver the ECM derivative, gelatin, after the polymer has adhered to tissue and reached physiological temperature. This work is based on the hypothesis that the discharge of gelatin will enhance the biocompatibility of the material by covalently reacting with, or "end-capping", the aldehyde functionalities within the gel that did not participate in bonding with tissue upon contact. As a comparison, formulations were also created without CS aldehyde and with an alternative adhesion mediator, mucoadhesive calcium alginate particles. Gels formed from blends of PNIPAAm-g-CS and CS aldehyde exhibited increased adhesive strength compared to PNIPAAm-g-CS alone (p<0.05). However, the addition of gelatin-loaded liposomes to the blend significantly decreased the adhesive strength (p<0.05). The encapsulation of alginate microparticles within PNIPAAm-g-CS gels caused the tensile strength to increase twofold over that of PNIPAAm-g-CS blends with CS aldehyde (p<0.05). Cytocompatibility studies indicate that formulations containing alginate particles exhibit reduced cytotoxicity over those containing CS aldehyde. Overall, the results indicated that the adhesives composed of alginate microparticles encapsulated in PNIPAAm-g-CS have the potential to serve as a scaffold for IVD regeneration.

  18. MRI-based polymer gel dosimetry for validating plans with multiple matrices in Gamma Knife stereotactic radiosurgery.

    Science.gov (United States)

    Gopishankar, N; Watanabe, Yoichi; Subbiah, Vivekanandhan

    2011-01-31

    One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: TR = 7 s, echo step = 13.6 ms, field-of-view = 256 mm × 256 mm, and pixel size = 1 mm × 1 mm. Interleaved acquisition mode was used to obtain 15 to 45 2-mm-thick slices. Using a calibration relationship between absorbed dose and the spin-spin relaxation rate (R2), we converted R2 images to dose images. MATLAB-based in-house programs were used for R2 estimation and dose comparison. Gamma-index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets.

  19. High-temperature solvent stability of sol-gel germania triblock polymer coatings in capillary microextraction on-line coupled to high-performance liquid chromatography.

    Science.gov (United States)

    Segro, Scott S; Malik, Abdul

    2010-09-10

    Germania-based sol-gel organic-inorganic hybrid coatings were prepared for on-line coupling of capillary microextraction with high-performance liquid chromatography. For this, a germania-based sol-gel precursor, tetra-n-butoxygermane and a hydroxy-terminated triblock copolymer, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) were used. These sol-gel germania triblock polymer coatings were chemically anchored to the inner walls of a fused silica capillary (0.25 mm I.D.) in course of its evolution from the sol solution. Scanning electron microscopy images of the sol-gel germania triblock polymer coating were obtained to estimate the coating thickness. For the first time, the analyte distribution constants between a sol-gel germania organic-inorganic hybrid coating and the samples (K(cs)) were determined. For a variety of analytes from different chemical classes, including polycyclic aromatic hydrocarbons (PAHs), ketones, alcohols, phenols and amines, the K(cs) values ranged from 8.1 x 10(1) to 5.6 x 10(4). Also, for the first time, the stability of the sol-gel germania-based coating in high-temperature reversed-phase solvent environment was evaluated. The sol-gel germania triblock polymer coatings were capable of surviving exposure to high-temperature solvent conditions (200 degrees C) with little change in extraction capabilities. This demonstrates that sol-gel germania triblock polymer hybrid materials might be suitable for further applications in high-temperature HPLC. The reproducibility of the method for preparation of the sol-gel germania triblock polymer coatings was also evaluated, and the capillary-to-capillary RSD values ranged from 5.3 to 6.5%. The use of higher flow rates in extraction was found to significantly reduce the time required (from 30-40 to 10-15 min) to reach equilibrium between the sol-gel germania triblock polymer coating and the analytes in the sample solution.

  20. Electrochemical characterizations on MnO2 supercapacitors with potassium polyacrylate and potassium polyacrylate-co-polyacrylamide gel polymer electrolytes

    KAUST Repository

    Lee, Kuang-Tsin

    2009-11-01

    MnO2·nH2O supercapacitors with potassium polyacrylate (PAAK) and potassium polyacrylate-co-polyacrylamide (PAAK-co-PAAM) gel polymer electrolytes (GPEs) having the weight compositions of polymer:KCl:H2O = 9%:6.7%:84.3% have been characterized for their electrochemical performance. Compared with the liquid electrolyte (LE) counterpart, the GPE cells exhibit remarkable (∼50-130%) enhancement in specific capacitance of the oxide electrode, and the extent of the enhancement increases with increasing amount of the carboxylate groups in the polymers as well as with increasing oxide/electrolyte interfacial area. In situ X-ray absorption near-edge structure (XANES) analysis indicates that the oxide electrodes of the GPE cells possess higher Mn-ion valences and are subjected to greater extent of valence variation than that of the LE cell upon charging/discharging over the same potential range. Copolymerization of PAAK with PAAM greatly improves the cycling stability of the MnO2·nH2O electrode, and the improvement is attributable to the alkaline nature of the amino groups. Both GPEs exhibit ionic conductivities greater than 1.0 × 10-1 S cm-1 and are promising for high-rate applications. © 2009 Elsevier Ltd. All rights reserved.

  1. Preparation and characterization of PAN–KI complexed gel polymer electrolytes for solid-state battery applications

    Indian Academy of Sciences (India)

    N KRISHNA JYOTHI; K K VENKATARATNAM; P NARAYANA MURTY; K VIJAYA KUMAR

    2016-08-01

    The free standing and dimensionally stable gel polymer electrolyte films of polyacrylonitrile (PAN): potassium iodide (KI) of different compositions, using ethylene carbonate as a plasticizer and dimethyl formamide as solvent, are prepared by adopting ‘solution casting technique’ and these films are examined for their conductivities. The structural, miscibility and the chemical rapport between PAN and KI are investigated using X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry methods. The conductivity is enhanced with the increase in KI concentration and temperature. The maximum conductivity at 30$^{\\circ}$C is found to be $2.089 \\times 10^{−5}$ S cm$^{−1}$ for PAN:KI (70:30) wt%, which is nine orders greater than that of pure PAN (${\\lt}10^{−14}$ S cm$^{−1}$). The conductivity-temperature dependence of these polymer electrolyte films obeys Arrhenius behaviour with activation energy ranging from 0.358 to 0.478 eV. The conducting carriers of charge transport in these polymer electrolyte films are identified by Wagner’s polarization technique and it is found that the charge transport is predominantlydue to ions. The better conducting sample is used to fabricate the battery with configuration K/PAN $+$ KI/I$_2$ $+$ C $+$ electrolyte and good discharge characteristics of battery are observed.

  2. Verification of dose volume histograms in stereotactic radiosurgery and radiotherapy using polymer gel and MRI

    Science.gov (United States)

    Šemnická, Jitka; Novotný, Josef, Jr.; Spěváček, Václav; Garčic, Jirí; Steiner, Martin; Judas, Libor

    2006-12-01

    In this work we focus on dose volume histograms (DVHs) measurement in stereotactic radiosurgery (SR) performed with the Leksell gamma knife (ELEKTA Instrument AB, Stockholm, Sweden) and stereotactic radiotherapy (SRT) performed with linear accelerator 6 MV Varian Clinac 2100 C/D (Varian Medical Systems, Palo Alto, USA) in conjunction with BrainLAB stereotactic system (BrainLAB, Germany) using modified BANG gel and magnetic resonance imaging (MRI). The aim of the experiments was to investigate a method for acquiring entire dose volume information from irradiated gel dosimeter and calculate DVHs.

  3. RapidArc treatment verification in 3D using polymer gel dosimetry and Monte Carlo simulation

    DEFF Research Database (Denmark)

    Ceberg, Sofie; Gagne, Isabel; Gustafsson, Helen;

    2010-01-01

    and MC simulations, thus investigating any discrepancy between the planned dose delivery and the actual delivery. Additionally, the reproducibility of the delivery was investigated using repeated gel measurements. A prostate treatment plan was delivered to a 1.3 liter nPAG gel phantom using one single...... was within 2.5% (1SD). A 3D gamma analysis between the dose matrices were carried out using gamma criteria 3%/3 mm and 5%/5 mm (% dose difference and mm distance to agreement) within the volume enclosed by the 50% isodose surface (VOI50) and the 90% isodose surface (VOI90), respectively. All comparisons...

  4. Experimental and theoretical investigation of time-setting polymer gels in porous media

    International Nuclear Information System (INIS)

    This paper comprises studies of the kinetics of the xanthan/chromium gel system. The central objective of this work is to perform well-characterized core flow experiments with a simple gelling system that may then be mathematically simulated to obtain a detailed knowledge of the processes that are occurring. Gamma-labeled /sup 51/Cr is used so that in-situ chromium profiles may be observed during gel emplacement. These are required to distinguish between different kinetic/transport models because effluent profiles alone are insufficient for this purpose. A generalized multicomponent transport equation including terms describing the crosslinking reaction is used to simulate the experiments

  5. Electrochemical Hydrogel Lithography of Calcium-Alginate Hydrogels for Cell Culture

    Directory of Open Access Journals (Sweden)

    Fumisato Ozawa

    2016-08-01

    Full Text Available Here we propose a novel electrochemical lithography methodology for fabricating calcium-alginate hydrogels having controlled shapes. We separated the chambers for Ca2+ production and gel formation with alginate with a semipermeable membrane. Ca2+ formed in the production chamber permeated through the membrane to fabricate a gel structure on the membrane in the gel formation chamber. When the calcium-alginate hydrogels were modified with collagen, HepG2 cells proliferated on the hydrogels. These results show that electrochemical hydrogel lithography is useful for cell culture.

  6. Note: Utilization of polymer gel as a bolus compensator and a dosimeter in the near-surface buildup region for breast-conserving therapy

    Energy Technology Data Exchange (ETDEWEB)

    Fuse, Hiraku, E-mail: fuseh@ipu.ac.jp; Inohira, Masaya; Kawamura, Hiraku; Fujisaki, Tatsuya [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Inashiki-gun, Ibaraki 300-0331 (Japan); Shinoda, Kazuya [Graduate School of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki (Japan); Department of Radiological Technology, Tsukuba Medical Center Hospital, Tsukuba (Japan); Miyamoto, Katsumi [Department of Radiological Technology, Tsukuba Medical Center Hospital, Tsukuba (Japan); Sakae, Takeji [Faculty of Medicine, University of Tsukuba, Tsukuba (Japan)

    2015-09-15

    Tangential beam radiotherapy is routinely used for radiation therapy after breast conserving surgery. A tissue-equivalent bolus placed on the irradiated area shifts the depth of the dose distribution; this bolus provides uniform dose distribution to the breast. The gel bolus made by the BANG-Pro{sup ®} polymer gel and in an oxygen non-transmission pack was applicable as a dosimeter to measure dose distribution in near-surface buildup region. We validated the use of the gel bolus to improve in the whole-breast/chest wall, including the near-surface buildup region.

  7. Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

    International Nuclear Information System (INIS)

    Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements.

  8. Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Pavoni, J. F.; Pike, T. L.; Snow, J.; DeWerd, L.; Baffa, O. [Departamento de Fisica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Av. Bandeirantes, 3900 - CEP 14040-901 - Bairro Monte Alegre - Ribeirao Preto, SP (Brazil); Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin, 1111 Highland Avenue, B1002 WIMR, Madison, Wisconsin 53705-2275 (United States); Departamento de Fisica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Av. Bandeirantes, 3900 - CEP 14040-901 - Bairro Monte Alegre - Ribeirao Preto, SP (Brazil)

    2012-05-15

    Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements.

  9. Inorganic Nanoparticle Nucleation on Polymer Matrices

    Science.gov (United States)

    Kosteleski, Adrian John

    The introduction of inorganic nanoparticles into organic materials enhances both the mechanical and chemical properties of the material. Metallic nanoparticles, like silver and gold, have been introduced into polymers for use as antimicrobial coatings or dielectric materials, respectively. The challenge in creating these materials currently is the difficulty to homogeneously disperse the particles throughout the polymer matrix. The uneven dispersion of nanoparticles can lead to less than optimal quality and undesired properties. By creating a polymer nanocomposite material with well-controlled size inorganic materials that are evenly dispersed throughout the polymer matrix; we can improve the materials performance and properties. The objective for this research is to use polymer networks for the in situ mineralization of silver and other metallic materials to create intricate inorganic structures. The work performed here studied the ability to nucleate silver nanoparticles using poly (acrylic acid) (PAA) as the templating agent. Ionic silver was chemically reduced by sodium borohydride (NaBH4) in the presence of PAA. The effect of varying reactant concentrations of silver, NaBH 4, and PAA on particle size was studied. Reaction conditions in terms of varying temperature and pH levels of the reaction solution were monitored to observe the effect of silver nanoparticle size, shape, and concentration. By monitoring the UV spectra over time the reaction mechanism of the silver reduction process was determined to be an autocatalytic process: a period of slow, continuous nucleation followed by rapid, autocatalytic growth. The reaction kinetics for this autocatalytic process is also reported. PAA was crosslinked both chemically and physically to 3 biopolymers; ELP, an elastin like peptide, cotton fabrics, and calcium alginate hydrogels. Various compositions of PAA were physically crosslinked with calcium alginate gels to design an antimicrobial hydrogel for use in wound

  10. HAp granules encapsulated oxidized alginate-gelatin-biphasic calcium phosphate hydrogel for bone regeneration.

    Science.gov (United States)

    Sarker, Avik; Amirian, Jhaleh; Min, Young Ki; Lee, Byong Taek

    2015-11-01

    Bone repair in the critical size defect zone using 3D hydrogel scaffold is still a challenge in tissue engineering field. A novel type of hydrogel scaffold combining ceramic and polymer materials, therefore, was fabricated to meet this challenge. In this study, oxidized alginate-gelatin-biphasic calcium phosphate (OxAlg-Gel-BCP) and spherical hydroxyapatite (HAp) granules encapsulated OxAlg-Gel-BCP hydrogel complex were fabricated using freeze-drying method. Detailed morphological and material characterizations of OxAlg-Gel-BCP hydrogel (OGB00), 25wt% and 35wt% granules encapsulated hydrogel (OGB25 and OGB35) were carried out for micro-structure, porosity, chemical constituents, and compressive stress analysis. Cell viability, cell attachment, proliferation and differentiation behavior of rat bone marrow-derived stem cell (BMSC) on OGB00, OGB25 and OGB35 scaffolds were confirmed by MTT assay, Live-Dead assay, and confocal imaging in vitro experiments. Finally, OGB00 and OGB25 hydrogel scaffolds were implanted in the critical size defect of rabbit femoral chondyle for 4 and 8 weeks. The micro-CT analysis and histological studies conducted by H&E and Masson's trichrome demonstrated that a significantly higher (***phydrogel than in OxAlg-Gel-BCP complex alone. All results taken together, HAp granules encapsulated OxAlg-Gel-BCP system can be a promising 3D hydrogel scaffold for the healing of a critical bone defect.

  11. A green and environment-friendly gel polymer electrolyte with higher performances based on the natural matrix of lignin

    Science.gov (United States)

    Gong, Sheng-Dong; Huang, Yun; Cao, Hai-Jun; Lin, Yuan-Hua; Li, Yang; Tang, Shui-Hua; Wang, Ming-Shan; Li, Xing

    2016-03-01

    In order to explore one truly green and environment-friendly gel polymer electrolyte (GPE), the natural biopolymer of lignin is firstly all over the world used as matrix to prepare GPE. The electrolyte membrane based on lignin can be easily fabricated just with lignin, liquid electrolyte and distilled water. Through comprehensive investigation of obtained GPE, it is found that the liquid electrolyte uptake reaches up to 230 wt.%; before 100 °C, GPE does not lose any weight and is thermal stable; at room temperature the ion conductivity is 3.73 mS cm-1; the amazing property of lithium ion transference number is high up to 0.85; GPE expresses complete electrochemical stability before 7.5 V and favorable compatibility with lithium anode; the outstanding cell performance of C-rate and cycle capacity. All these remarkably excellent performances endow lignin with application potential in GPE used in lithium ion batteries (LIBs) with higher performances.

  12. A pH-responsive supramolecular polymer gel as an enteric elastomer for use in gastric devices.

    Science.gov (United States)

    Zhang, Shiyi; Bellinger, Andrew M; Glettig, Dean L; Barman, Ross; Lee, Young-Ah Lucy; Zhu, Jiahua; Cleveland, Cody; Montgomery, Veronica A; Gu, Li; Nash, Landon D; Maitland, Duncan J; Langer, Robert; Traverso, Giovanni

    2015-10-01

    Devices resident in the stomach-used for a variety of clinical applications including nutritional modulation for bariatrics, ingestible electronics for diagnosis and monitoring, and gastric-retentive dosage forms for prolonged drug delivery-typically incorporate elastic polymers to compress the devices during delivery through the oesophagus and other narrow orifices in the digestive system. However, in the event of accidental device fracture or migration, the non-degradable nature of these materials risks intestinal obstruction. Here, we show that an elastic, pH-responsive supramolecular gel remains stable and elastic in the acidic environment of the stomach but can be dissolved in the neutral-pH environment of the small and large intestines. In a large animal model, prototype devices with these materials as the key component demonstrated prolonged gastric retention and safe passage. These enteric elastomers should increase the safety profile for a wide range of gastric-retentive devices.

  13. Structure and biological response of polymer/silica nanocomposites prepared by sol-gel technique

    OpenAIRE

    Vallés-Lluch, A.; COSTA, E.; Ferrer, G. Gallego; Pradas, M. Monleón; Salmerón-Sánchez, M.

    2010-01-01

    Abstract Structure of P(EMA-co-HEA)/SiO2 nanocomposites with silica content in the range from 0 to 30 %wt was correlated with cell behaviour on substrates of those compositions by making use of two different populations of primary human cells: articular cartilage chondrocytes and dental pulp cells. Substrates were prepared by the simultaneous copolymerization of the organic monomers and the sol-gel reaction of the silica precursor in different proportions, which led to weight fract...

  14. Multi-responsive physical gels formed by a biosynthetic asymmetric triblock protein polymer and a polyanion

    NARCIS (Netherlands)

    Pham, T.H.T.; Wang, J.; Werten, M.W.T.; Snijkers, F.; Wolf, de F.A.; Cohen Stuart, M.A.; Gucht, van der J.

    2013-01-01

    We report the design, production and characterization of a biosynthetic asymmetric triblock copolymer which consists of one collagen-like and one cationic block spaced by a hydrophilic random coiled block. The polymer associates into micelles when a polyanion is added due to the electrostatic intera

  15. High performance of transferring lithium ion for polyacrylonitrile-interpenetrating crosslinked polyoxyethylene network as gel polymer electrolyte.

    Science.gov (United States)

    Kuo, Ping-Lin; Wu, Ching-An; Lu, Chung-Yu; Tsao, Chin-Hao; Hsu, Chun-Han; Hou, Sheng-Shu

    2014-03-12

    A polyacrylonitrile (PAN)-interpenetrating cross-linked polyoxyethylene (PEO) network (named XANE) was synthesized acting as separator and as gel polymer electrolytes simultaneously. SEM images show that the surface of the XANE membrane is nonporous, comparing to the surface of the commercial separator to be porous. This property results in excellent electrolyte uptake amount (425 wt %), and electrolyte retention for XANE membrane, significantly higher than that of commercial separator (200 wt %). The DSC result indicates that the PEO crystallinity is deteriorated by the cross-linked process and was further degraded by the interpenetration of the PAN. The XANE membrane shows significantly higher ionic conductivity (1.06-8.21 mS cm(-1)) than that of the commercial Celgard M824 separator (0.45-0.90 mS cm(-1)) ascribed to the high electrolyte retention ability of XANE (from TGA), the deteriorated PEO crystallinity (from DSC) and the good compatibility between XANE and electrode (from measuring the interfacial-resistance). For battery application, under all charge/discharge rates (from 0.1 to 3 C), the specific half-cell capacities of the cell composed of the XANE membrane are all higher than those of the aforementioned commercial separator. More specifically, the cell composed of the XANE membrane has excellent cycling stability, that is, the half-cell composed of the XANE membrane still exhibited more than 97% columbic efficiency after 100 cycles at 1 C. The above-mentioned advantageous properties and performances of the XANE membrane allow it to act as both an ionic conductor as well as a separator, so as to work as separator-free gel polymer electrolytes. PMID:24521309

  16. Sol-Gel Material-Enabled Electro-Optic Polymer Modulators.

    Science.gov (United States)

    Himmelhuber, Roland; Norwood, Robert A; Enami, Yasufumi; Peyghambarian, Nasser

    2015-07-27

    Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed.

  17. Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry

    International Nuclear Information System (INIS)

    This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors >15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data

  18. Enhanced ultraviolet photocatalytic activity of Ag/ZnO nanoparticles synthesized by modified polymer-network gel method

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y. H.; Xu, M., E-mail: hsuming-2001@aliyun.com [Southwest University for Nationalities, Key Laboratory of Information Materials of Sichuan Province, School of Electrical and Information Engineering (China); Xu, L. X. [Nanyang Technological University, Plasma Sources and Applications Center, NIE (Singapore); Zhang, C. L.; Zhang, Q. P.; Xu, X. N. [Southwest University for Nationalities, Key Laboratory of Information Materials of Sichuan Province, School of Electrical and Information Engineering (China); Xu, S. [Nanyang Technological University, Plasma Sources and Applications Center, NIE (Singapore); Ostrikov, K., E-mail: kostya.ostrikov@qut.edu.au [Queensland University of Technology, Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering (Australia)

    2015-09-15

    Ag/ZnO nanoparticle (NP) heterostructures are synthesized through a modified polymer-network gel method in which glucose is added to the precursor solution to prevent the gel from drastically shrinking during drying of the aqueous solution. Structural and optical properties of the samples are characterized by a range of techniques including XRD, SEM, TEM, XPS, UV–Vis, and PL. The high-quality Ag-ZnO heterostructure is evidenced clearly by high-resolution TEM. The Ag/ZnO heterostructure nanocomposites exhibit a higher photocatalytic activity in the degradation of methyl orange than pure ZnO. Especially, Ag/ZnO NP heterostructures with the Ag/Zn molar ratio of 5:95 (sample ZA-5) show the highest degradation efficiency, which is 11 times higher compared with pure ZnO. The photoluminescence properties of the heterostructures and O defect states are studied to well explain the observed photocatalytic effects. ZA-5 also exhibits competitive photocatalytic activity for the degradation of other pollutant dyes such as Methylene blue and Rhodamine B compared with the recently reported techniques, while showing excellent catalyst photostability as well as offering simplicity and reliability.

  19. 3-V Solid-State Flexible Supercapacitors with Ionic-Liquid-Based Polymer Gel Electrolyte for AC Line Filtering.

    Science.gov (United States)

    Kang, Yu Jin; Yoo, Yongju; Kim, Woong

    2016-06-01

    State-of-the-art solid-state flexible supercapacitors with sufficiently fast response speed for AC line filtering application suffer from limited energy density. One of the main causes of the low energy density is the low cell voltage (1 V), which is limited by aqueous-solution-based gel electrolytes. In this work, we demonstrate for the first time a 3-V flexible supercapacitor for AC line filtering based on an ionic-liquid-based polymer gel electrolyte and carbon nanotube electrode material. The flexible supercapacitor exhibits an areal energy density that is more than 20 times higher than that of the previously demonstrated 1-V flexible supercapacitor (0.66 vs 0.03 μWh/cm(2)) while maintaining excellent capacitive behavior at 120 Hz. The supercapacitor shows a maximum areal power density of 1.5 W/cm(2) and a time constant of 1 ms. The improvement of the cell voltage while maintaining the fast-response capability greatly improves the potential of supercapacitors for high-frequency applications in wearable and/or portable electronics. PMID:27167760

  20. Effect of acid dopants in biodegradable gel polymer electrolyte and the performance in an electrochemical double layer capacitor

    Science.gov (United States)

    Sudhakar, Y. N.; Selvakumar, M.; Krishna Bhat, D.

    2015-09-01

    Proton-conducting biodegradable gellan gum gel polymer electrolytes (GPEs) have been prepared using three different dopants, namely ortho-phosphoric (o-H3PO4), sulfuric (H2SO4) and hydrochloric acids (HCl). The GPEs were cross-linked using borax. The polymeric gels were characterized by spectroscopic, thermal, ionic conductivities and dielectric measurements. Proton conductivity was in the range of 5.1 × 10-3 to 3.7 × 10-4 s cm-1 and activation energies were between 0.14 meV and 0.19 meV, at different temperatures. Among the doped acids, the H3PO4 doped GPE exhibited thermal stability at varying temperature. Electrochemical double layer capacitors (EDLCs) were fabricated using activated carbon as electrode material and GPEs. The EDLCs were tested using cyclic voltammetry, ac impedance spectroscopic and galvanostatic charge-discharge techniques. The maximum specific capacitance value was 146 F g-1 at a scan rate of 2 mV s-1. Quite stable values were obtained at a constant current density up to 1000 cycles.

  1. Hydrogels of sodium alginate in cationic surfactants: Surfactant dependent modulation of encapsulation/release toward Ibuprofen.

    Science.gov (United States)

    Jabeen, Suraya; Chat, Oyais Ahmad; Maswal, Masrat; Ashraf, Uzma; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2015-11-20

    The interaction of cetyltrimethylammoium bromide (CTAB) and its gemini homologue (butanediyl-1,4-bis (dimethylcetylammonium bromide), 16-4-16 with biocompatible polymer sodium alginate (SA) has been investigated in aqueous medium. Addition of K2CO3 influences viscoelastic properties of surfactant impregnated SA via competition between electrostatic and hydrophobic interactions. Viscosity of these polymer-surfactant systems increases with increase in concentration of K2CO3, and a cryogel is formed at about 0.5M K2CO3 concentration. The thermal stability of gel (5% SA+0.5M K2CO3) decreases with increase in surfactant concentration, a minimum is observed with increase in 16-4-16 concentration. The impact of surfactant addition on the alginate structure vis-à-vis its drug loading capability and release thereof was studied using Ibuprofen (IBU) as the model drug. The hydrogel with 16-4-16 exhibits higher IBU encapsulation and faster release in comparison to the one containing CTAB. This higher encapsulation-cum-faster release capability has been related to micelle mediated solubilization and greater porosity of the hydrogel with gemini surfactant. PMID:26344266

  2. Hydrogels of sodium alginate in cationic surfactants: Surfactant dependent modulation of encapsulation/release toward Ibuprofen.

    Science.gov (United States)

    Jabeen, Suraya; Chat, Oyais Ahmad; Maswal, Masrat; Ashraf, Uzma; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2015-11-20

    The interaction of cetyltrimethylammoium bromide (CTAB) and its gemini homologue (butanediyl-1,4-bis (dimethylcetylammonium bromide), 16-4-16 with biocompatible polymer sodium alginate (SA) has been investigated in aqueous medium. Addition of K2CO3 influences viscoelastic properties of surfactant impregnated SA via competition between electrostatic and hydrophobic interactions. Viscosity of these polymer-surfactant systems increases with increase in concentration of K2CO3, and a cryogel is formed at about 0.5M K2CO3 concentration. The thermal stability of gel (5% SA+0.5M K2CO3) decreases with increase in surfactant concentration, a minimum is observed with increase in 16-4-16 concentration. The impact of surfactant addition on the alginate structure vis-à-vis its drug loading capability and release thereof was studied using Ibuprofen (IBU) as the model drug. The hydrogel with 16-4-16 exhibits higher IBU encapsulation and faster release in comparison to the one containing CTAB. This higher encapsulation-cum-faster release capability has been related to micelle mediated solubilization and greater porosity of the hydrogel with gemini surfactant.

  3. Microencapsulation of bull spermatozoa: Its viability in alginate-egg yolk media

    OpenAIRE

    2015-01-01

    Microencapsulation of spermatozoa is a process to entrap a number of spermatozoa in microcapsule. Alginate, as a natural polymer polysaccharide is commonly used in cell microencapsulation. Tris Yolk Citrate buffer is a good buffer for spermatozoa dilution, therefore this experiment aimed to determine optimal concentration of alginate and egg yolk to sperm quality in bull spermatozoa microencapsulation. Concentration of egg yolk and alginate in media of encapsulation were determined in applica...

  4. An ion-imprinted polymer supported by attapulgite with a chitosan incorporated sol-gel process for selective separation of Ce(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    Chun Xiang Li; Jian Ming Pan; Jie Gao; Yong Sheng Yan; Gan Qing Zhao

    2009-01-01

    The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the synthesis of a new attapulgite-supported polymer for selective separation of Ce(Ⅲ) from aqueous solution. The imprinting mechanism of prepared ion-imprinted polymer were discussed with the Characteristics of FT-IR and SEM. Results from the experiments of adsorption capacity and selectivity suggested that ion-imprinted polymer offered a fast kinetics for the adsorption of Ce(Ⅲ) under the optimum conditions. Its maximum adsorption capacity was 38.02 mg/g, and the selective recognition towards Ce(Ⅲ) was much higher than that of the non-imprinted polymer and attapulgite. The prepared functional polymer was shown to be promising for selective separation and enrichment of trace Ce(Ⅲ) in environmental samples.

  5. Assessment of the effects of CT dose in averaged x-ray CT images of a dose-sensitive polymer gel

    International Nuclear Information System (INIS)

    The signal-to-noise ratio achievable in x-ray computed tomography (CT) images of polymer gels can be increased by averaging over multiple scans of each sample. However, repeated scanning delivers a small additional dose to the gel which may compromise the accuracy of the dose measurement. In this study, a NIPAM-based polymer gel was irradiated and then CT scanned 25 times, with the resulting data used to derive an averaged image and a ''zero-scan'' image of the gel. Comparison between these two results and the first scan of the gel showed that the averaged and zero-scan images provided better contrast, higher contrast-to- noise and higher signal-to-noise than the initial scan. The pixel values (Hounsfield units, HU) in the averaged image were not noticeably elevated, compared to the zero-scan result and the gradients used in the linear extrapolation of the zero-scan images were small and symmetrically distributed around zero. These results indicate that the averaged image was not artificially lightened by the small, additional dose delivered during CT scanning. This work demonstrates the broader usefulness of the zero-scan method as a means to verify the dosimetric accuracy of gel images derived from averaged x-ray CT data

  6. Preparation and adsorption behavior of berberine hydrochloride imprinted polymers by using silica gel as sacrificed support material

    Science.gov (United States)

    Li, Hui; Li, Yuzhuo; Li, Zhiping; Peng, Xiyang; Li, Yanan; Li, Gui; Tan, Xianzhou; Chen, Gongxi

    2012-03-01

    Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2 μmol g-1 and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

  7. Preparation and adsorption behavior of berberine hydrochloride imprinted polymers by using silica gel as sacrificed support material

    Energy Technology Data Exchange (ETDEWEB)

    Li Hui, E-mail: lihuijsdx@163.com [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan Jishou, 416000 (China); Li Yuzhuo [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan Jishou, 416000 (China); Li Zhiping [College of Chemistry and Chemical Engineering, Jishou University, Hunan Jishou, 416000 (China); Peng Xiyang; Li Yanan; Li Gui; Tan Xianzhou; Chen Gongxi [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan Jishou, 416000 (China)

    2012-03-01

    Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2 {mu}mol g{sup -1} and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

  8. Field-theoretic model of inhomogeneous supramolecular polymer networks and gels.

    Science.gov (United States)

    Mohan, Aruna; Elliot, Richard; Fredrickson, Glenn H

    2010-11-01

    We present a field-theoretic model of the gelation transition in inhomogeneous reversibly bonding systems and demonstrate that our model reproduces the classical Flory-Stockmayer theory of gelation in the homogeneous limit. As an illustration of our model in the context of inhomogeneous gelation, we analyze the mean-field behavior of an equilibrium system of reacting trifunctional units in a good solvent confined within a slit bounded by parallel, repulsive walls. Our results indicate higher conversions and, consequently, higher concentrations of gel following the gelation transition near the center of the slit relative to the edges. PMID:21054065

  9. Microencapsulation of probiotics using sodium alginate

    Directory of Open Access Journals (Sweden)

    Mariana de Araújo Etchepare

    2015-07-01

    Full Text Available The consumption of probiotics is constantly growing due to the numerous benefits conferred on the health of consumers. In this context, Microencapsulation is a technology that favors the viability of probiotic cultures in food products, mainly by the properties of protection against adverse environmental conditions and controlled release. Currently there are different procedures for microencapsulation using polymers of various types of natural and synthetic origin. The use of sodium alginate polymers is one of the largest potential application in the encapsulation of probiotics because of their versatility, biocompatibility and toxicity exemption. The aim of this review is to present viable encapsulation techniques of probiotics with alginate, emphasizing the internal ionic gelation and external ionic gelation, with the possibility of applying, as well as promising for improving these techniques.

  10. Oxidation increases mucin polymer cross-links to stiffen airway mucus gels.

    Science.gov (United States)

    Yuan, Shaopeng; Hollinger, Martin; Lachowicz-Scroggins, Marrah E; Kerr, Sheena C; Dunican, Eleanor M; Daniel, Brian M; Ghosh, Sudakshina; Erzurum, Serpel C; Willard, Belinda; Hazen, Stanley L; Huang, Xiaozhu; Carrington, Stephen D; Oscarson, Stefan; Fahy, John V

    2015-02-25

    Airway mucus in cystic fibrosis (CF) is highly elastic, but the mechanism behind this pathology is unclear. We hypothesized that the biophysical properties of CF mucus are altered because of neutrophilic oxidative stress. Using confocal imaging, rheology, and biochemical measures of inflammation and oxidation, we found that CF airway mucus gels have a molecular architecture characterized by a core of mucin covered by a web of DNA and a rheological profile characterized by high elasticity that can be normalized by chemical reduction. We also found that high levels of reactive oxygen species in CF mucus correlated positively and significantly with high concentrations of the oxidized products of cysteine (disulfide cross-links). To directly determine whether oxidation can cross-link mucins to increase mucus elasticity, we exposed induced sputum from healthy subjects to oxidizing stimuli and found a marked and thiol-dependent increase in sputum elasticity. Targeting mucin disulfide cross-links using current thiol-amino structures such as N-acetylcysteine (NAC) requires high drug concentrations to have mucolytic effects. We therefore synthesized a thiol-carbohydrate structure (methyl 6-thio-6-deoxy-α-D-galactopyranoside) and found that it had stronger reducing activity than NAC and more potent and fast-acting mucolytic activity in CF sputum. Thus, oxidation arising from airway inflammation or environmental exposure contributes to pathologic mucus gel formation in the lung, which suggests that it can be targeted by thiol-modified carbohydrates.

  11. Oxidation increases mucin polymer cross-links to stiffen airway mucus gels.

    Science.gov (United States)

    Yuan, Shaopeng; Hollinger, Martin; Lachowicz-Scroggins, Marrah E; Kerr, Sheena C; Dunican, Eleanor M; Daniel, Brian M; Ghosh, Sudakshina; Erzurum, Serpel C; Willard, Belinda; Hazen, Stanley L; Huang, Xiaozhu; Carrington, Stephen D; Oscarson, Stefan; Fahy, John V

    2015-02-25

    Airway mucus in cystic fibrosis (CF) is highly elastic, but the mechanism behind this pathology is unclear. We hypothesized that the biophysical properties of CF mucus are altered because of neutrophilic oxidative stress. Using confocal imaging, rheology, and biochemical measures of inflammation and oxidation, we found that CF airway mucus gels have a molecular architecture characterized by a core of mucin covered by a web of DNA and a rheological profile characterized by high elasticity that can be normalized by chemical reduction. We also found that high levels of reactive oxygen species in CF mucus correlated positively and significantly with high concentrations of the oxidized products of cysteine (disulfide cross-links). To directly determine whether oxidation can cross-link mucins to increase mucus elasticity, we exposed induced sputum from healthy subjects to oxidizing stimuli and found a marked and thiol-dependent increase in sputum elasticity. Targeting mucin disulfide cross-links using current thiol-amino structures such as N-acetylcysteine (NAC) requires high drug concentrations to have mucolytic effects. We therefore synthesized a thiol-carbohydrate structure (methyl 6-thio-6-deoxy-α-D-galactopyranoside) and found that it had stronger reducing activity than NAC and more potent and fast-acting mucolytic activity in CF sputum. Thus, oxidation arising from airway inflammation or environmental exposure contributes to pathologic mucus gel formation in the lung, which suggests that it can be targeted by thiol-modified carbohydrates. PMID:25717100

  12. Ca alginate as scaffold for iron oxide nanoparticles synthesis

    Directory of Open Access Journals (Sweden)

    P. V. Finotelli

    2008-12-01

    Full Text Available Recently, nanotechnology has developed to a stage that makes it possible to process magnetic nanoparticles for the site-specific delivery of drugs. To this end, it has been proposed as biomaterial for drug delivery system in which the drug release rates would be activated by a magnetic external stimuli. Alginate has been used extensively in the food, pharmaceutical and biomedical industries for their gel forming properties in the presence of multivalent cations. In this study, we produced iron oxide nanoparticles by coprecipitation of Fe(III and Fe(II. The nanoparticles were entrapped in Ca alginate beads before and after alginate gelation. XRD analysis showed that particles should be associated to magnetite or maghemite with crystal size of 9.5 and 4.3 nm, respectively. Studies using Mössbauer spectroscopy corroborate the superparamagnetic behavior. The combination of magnetic properties and the biocompatibility of alginate suggest that this biomaterial may be used as biomimetic system.

  13. Chitosan and alginate scaffolds for bone tissue regeneration.

    Science.gov (United States)

    Olmez, S S; Korkusuz, P; Bilgili, H; Senel, S

    2007-06-01

    Polymeric scaffold for tissue regeneration was developed for veterinary applications. Oxytetracycline hydrochloride (OTC), which is a widely used antibiotic in veterinary medicine was chosen as the model compound. Gel formulations using chitosan and alginate were prepared in distilled water or in 1% (v/v) acetic acid solution. Sponges were also prepared by a freeze-drying process. Tripolyphosphate was used for cross-linking. Viscosity was decreased in the presence of OTC in chitosan gels whereas no difference was found with alginate gels. All gels showed pseudoplastic behaviour. Water absorption capacity was highest with chitosan/alginate sponges. The solvent used for preparation of the chitosan gels was found to affect the release of OTC. The release of OTC from the sponges was increased by cross-linking. Chitosan/alginate sponges showed the slowest and lowest drug release among the developed sponge formulations in this study. The formulations were found to be biocompatible, inducing no adverse reaction in vivo on surgically formed bone defects of radius of rabbits. The level of organization of the remodelled new bone in the treatment groups was better than that of control. Incorporation of OTC into formulations did not show any considerable enhancing effect. PMID:17663189

  14. Antibacterial Peptide-Based Gel for Prevention of Medical Implanted-Device Infection.

    Directory of Open Access Journals (Sweden)

    Mihaela Mateescu

    Full Text Available Implanted medical devices are prone to infection. Designing new strategies to reduce infection and implant rejection are an important challenge for modern medicine. To this end, in the last few years many hydrogels have been designed as matrices for antimicrobial molecules destined to fight frequent infection found in moist environments like the oral cavity. In this study, two types of original hydrogels containing the antimicrobial peptide Cateslytin have been designed. The first hydrogel is based on alginate modified with catechol moieties (AC gel. The choice of these catechol functional groups which derive from mussel's catechol originates from their strong adhesion properties on various surfaces. The second type of gel we tested is a mixture of alginate catechol and thiol-terminated Pluronic (AC/PlubisSH, a polymer derived from Pluronic, a well-known biocompatible polymer. This PlubisSH polymer has been chosen for its capacity to enhance the cohesion of the composition. These two gels offer new clinical uses, as they can be injected and jellify in a few minutes. Moreover, we show these gels strongly adhere to implant surfaces and gingiva. Once gelled, they demonstrate a high level of rheological properties and stability. In particular, the dissipative energy of the (AC/PlubisSH gel detachment reaches a high value on gingiva (10 J.m-2 and on titanium alloys (4 J.m-2, conferring a strong mechanical barrier. Moreover, the Cateslytin peptide in hydrogels exhibited potent antimicrobial activities against P. gingivalis, where a strong inhibition of bacterial metabolic activity and viability was observed, indicating reduced virulence. Gel biocompatibility tests indicate no signs of toxicity. In conclusion, these new hydrogels could be ideal candidates in the prevention and/or management of periimplant diseases.

  15. 大茴香醛改性海藻酸钠凝胶的制备及释药性能%Preparation of alginate gel modified by anise aldehyde and controlled release

    Institute of Scientific and Technical Information of China (English)

    吴敏; 倪才华

    2012-01-01

    Hydrophobically modified alginate were obtained through acetalization of alginate with p-methoxy benzaldehyde catalysted by an acid. The modified alginate was characterized by FTIR spectra, fluorescence, transmission electronic microscopy, scanning e-lectronic microscopy, UV spectrum, thermal analysis. The modified alginate hydrogel was used as a drug carrier for encapsulation and release of bovine serum albumin. The results showed that drug loading ability and slow release were observed.%在酸催化下使海藻酸钠与对甲氧基苯甲醛(又名大茴香醛)发生缩醛化反应,使其疏水改性,并将其制备成凝胶.利用红外(FFIR)、荧光、透射电镜(TEM)、扫描电镜(SEM)、紫外、热重分析(TGA)对产物进行了表征.结果表明,大茴香醛成功地与海藻酸钠发生了反应.该凝胶可以作为药物载体对牛血清白蛋白进行包埋释放,结果发现,改性后的产物其载药率和缓释性能比未改性的海藻酸钠有了一定的提高.

  16. Polyelectrolyte gels

    Energy Technology Data Exchange (ETDEWEB)

    Segalman, D.J.; Witkowski, W.R.

    1995-06-01

    Polyelectrolyte (PE) gels are swollen polymer/solvent networks that undergo a reversible volume collapse/expansion through various types of stimulation. Applications that could exploit this large deformation and solvent expulsion/absorption characteristics include robotic {open_quotes}fingers{close_quotes} and drug delivery systems. The goals of the research were to first explore the feasibility of using the PE gels as {open_quotes}smart materials{close_quotes} - materials whose response can be controlled by an external stimulus through a feedback mechanism. Then develop a predictive capability to simulate the dynamic behavior of these gels. This involved experimentally characterizing the response of well-characterized gels to an applied electric field and other stimuli to develop an understanding of the underlying mechanisms which cause the volume collapse. Lastly, the numerical analysis tool was used to simulate various potential engineering devices based on PE gels. This report discusses the pursuit of those goals through experimental and computational means.

  17. Encapsulation of volatiles by homogenized partially-cross linked alginates.

    Science.gov (United States)

    Inguva, Pavan K; Ooi, Shing Ming; Desai, Parind M; Heng, Paul W S

    2015-12-30

    Cross-linked calcium alginate gels are too viscous to be efficaciously incorporated into spray dried formulations. Thus, viscosity reduction is essential to ensure the processability of calcium alginate gels to be sprayed. Viscosity reduction by high pressure homogenization can open new formulation possibilities. Presently, testing of microcapsule integrity is also limited because either single particle tests neglect collective particle behaviours in bulk or bulk testing methods are often associated with single compressions which may not fully characterize individual particle strengths. The aim of this study was sub-divided into three objectives. First objective was to evaluate the impact of high pressure homogenization on gel viscosity. Second objective was to explore the use of the homogenized gels with modified starch for microencapsulation by spray drying. The final objective was to develop a stamping system as microcapsule strength tester that can assess microcapsules in bulk and evaluate the impact of multiple compressions. Collectively, this study would lead towards developing a pressure-activated patch of microcapsules with encapsulated volatiles and the method to assess the patch efficacy. The alginate gels largely experienced an exponential decay in viscosity when homogenized. Furthermore, the homogenized gels were successfully incorporated in spray drying formulations for microencapsulation. The custom-designed microcapsule strength tester was successfully used and shown to possess the required sensitivity to discern batches of microcapsules containing volatiles to have different release profiles. Addition of homogenized gels strengthened the microcapsules only at high wall to core ratios with low mass-load alginate gels. High mass-load gels weaken the microcapsules, exhibiting a higher release at low stamping pressures and wrinkling on the microcapsules surface. PMID:26581772

  18. Dual phase polymer gel electrolyte based on non-woven poly(vinylidenefluoride-co-hexafluoropropylene)–layered clay nanocomposite fibrous membranes for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shubha, Nageswaran [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Prasanth, Raghavan [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute - NTU (ERI-N) Research Techno Plaza, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM-CREATE Center for Electromobility, Nanyang Technological University, Singapore 637553 (Singapore); Hoon, Hng Huey [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Srinivasan, Madhavi, E-mail: madhavi@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute - NTU (ERI-N) Research Techno Plaza, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM-CREATE Center for Electromobility, Nanyang Technological University, Singapore 637553 (Singapore)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► P(VdF-co-HFP)–clay nanocomposite based electrospun membranes are prepared. ► The membranes are used as polymer gel electrolyte (PGE) in lithium ion batteries. ► The composite PGE shows ionic conductivity of 5.5 mS cm{sup −1} at room temperature. ► Li/PGE/LiFePO{sub 4} cell delivers initial discharge capacity of 160 mAh g{sup −1}. ► The use of prepared electrolyte significantly improved the cell performance. -- Abstract: A new approach for fabricating polymer gel electrolytes (PGEs) based on electrospun poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) incorporated with layered nanoclay has been employed to enhance the ionic conductivity and electrochemical properties of P(VdF-co-HFP) without compromising its mechanical strength. The effect of layered nanoclay on properties of membranes has been evaluated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Surface morphology of the membranes has been studied using field-emission scanning electron microscopy (FE-SEM). Polymer gel electrolytes are prepared by soaking the fibrous membrane into 1 M LiPF{sub 6} in EC/DEC. The electrochemical studies show that incorporation of layered nanoclay into the polymer matrix greatly enhanced the ionic conductivity and compatibility with lithium electrodes. The charge–discharge properties and cycling performance of Li/LiFePO{sub 4} cells comprising nanocomposite polymer gel electrolytes have been evaluated at room temperature.

  19. Bioinspired design of a polymer gel sensor for the realization of extracellular Ca2+ imaging

    Science.gov (United States)

    Ishiwari, Fumitaka; Hasebe, Hanako; Matsumura, Satoko; Hajjaj, Fatin; Horii-Hayashi, Noriko; Nishi, Mayumi; Someya, Takao; Fukushima, Takanori

    2016-04-01

    Although the role of extracellular Ca2+ draws increasing attention as a messenger in intercellular communications, there is currently no tool available for imaging Ca2+ dynamics in extracellular regions. Here we report the first solid-state fluorescent Ca2+ sensor that fulfills the essential requirements for realizing extracellular Ca2+ imaging. Inspired by natural extracellular Ca2+-sensing receptors, we designed a particular type of chemically-crosslinked polyacrylic acid gel, which can undergo single-chain aggregation in the presence of Ca2+. By attaching aggregation-induced emission luminogen to the polyacrylic acid as a pendant, the conformational state of the main chain at a given Ca2+ concentration is successfully translated into fluorescence property. The Ca2+ sensor has a millimolar-order apparent dissociation constant compatible with extracellular Ca2+ concentrations, and exhibits sufficient dynamic range and excellent selectivity in the presence of physiological concentrations of biologically relevant ions, thus enabling monitoring of submillimolar fluctuations of Ca2+ in flowing analytes containing millimolar Ca2+ concentrations.

  20. Hierarchical self-assembly of telechelic star polymers: from soft patchy particles to gels and diamond crystals

    Science.gov (United States)

    Capone, Barbara; Coluzza, Ivan; Blaak, Ronald; Lo Verso, Federica; Likos, Christos N.

    2013-09-01

    The design of self-assembling materials in the nanometer scale focuses on the fabrication of a class of organic and inorganic subcomponents that can be reliably produced on a large scale and tailored according to their vast applications for, e.g. electronics, therapeutic vectors and diagnostic imaging agent carriers, or photonics. In a recent publication (Capone et al 2012 Phys. Rev. Lett. 109 238301), diblock copolymer stars have been shown to be a novel system, which is able to hierarchically self-assemble first into soft patchy particles and thereafter into more complex structures, such as the diamond and cubic crystal. The self-aggregating single star patchy behavior is preserved from extremely low up to high densities. Its main control parameters are related to the architecture of the building blocks, which are the number of arms (functionality) and the fraction of attractive end-monomers. By employing a variety of computational and theoretical tools, ranging from the microscopic to the mesoscopic, coarse-grained level in a systematic fashion, we investigate the crossover between the formation of microstructure versus macroscopic phase separation, as well as the formation of gels and networks in these systems. We finally show that telechelic star polymers can be used as building blocks for the fabrication of open crystal structures, such as the diamond or the simple-cubic lattice, taking advantage of the strong correlation between single-particle patchiness and lattice coordination at finite densities.

  1. pH-Mediated Fluorescent Polymer Particles and Gel from Hyperbranched Polyethylenimine and the Mechanism of Intrinsic Fluorescence.

    Science.gov (United States)

    Liu, Shi Gang; Li, Na; Ling, Yu; Kang, Bei Hua; Geng, Shuo; Li, Nian Bing; Luo, Hong Qun

    2016-02-23

    We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media. PMID:26829461

  2. Poly(vinyl Alcohol) Borate Gel Polymer Electrolytes Prepared by Electrodeposition and Their Application in Electrochemical Supercapacitors.

    Science.gov (United States)

    Jiang, Mengjin; Zhu, Jiadeng; Chen, Chen; Lu, Yao; Ge, Yeqian; Zhang, Xiangwu

    2016-02-10

    Gel polymer electrolytes (GPEs) have been studied for preparing flexible and compact electrochemical energy storage devices. However, the preparation and use of GPEs are complex, and most GPEs prepared through traditional methods do not have good wettability with the electrodes, which retard them from achieving their performance potential. In this study, these problems are addressed by conceiving and implementing a simple, but effective, method of electrodepositing poly(vinyl alcohol) potassium borate (PVAPB) GPEs directly onto the surfaces of active carbon electrodes for electrochemical supercapacitors. PVAPB GPEs serve as both the electrolyte and the separator in the assembled supercapacitors, and their scale and shape are determined solely by the geometry of the electrodes. PVAPB GPEs have good bonding to the active electrode materials, leading to excellent and stable electrochemical performance of the supercapacitors. The electrochemical performance of PVAPB GPEs and supercapacitors can be manipulated simply by adjusting the concentration of KCl salt used during the electrodeposition process. With a 0.9 M KCl concentration, the as-prepared supercapacitors deliver a specific capacitance of 65.9 F g(-1) at a current density of 0.1 A g(-1) and retain more than 95% capacitance after 2000 charge/discharge cycles at a current density of 1 A g(-1). These supercapacitors also exhibit intelligent high voltage self-protection function due to the electrolysis-induced cross-linking effect of PVAPB GPEs. PMID:26788748

  3. Increasing the Mechanical Strength of Block Polymer Ion Gels Through the Stepwise Self-Assembly of a Thermoresponsive ABC Triblock Terpolymer

    Science.gov (United States)

    Hall, Cecilia; Zhou, Can; Danielsen, Scott; Lodge, Timothy

    Blends of network-forming block polymers and ionic liquids have remarkable potential for solid electrolytes, as they allow the combination of desirable mechanical and electrical properties. While ABA triblock copolymers have successfully been implemented as the network component of ion gels, these networks contain looped defects, where the endblocks of the polymer loop back into the same spherical core instead of forming a bridge between two cores. We demonstrate that the ABC triblock terpolymer poly(ethylene-alt-propylene)-block-poly(ethylene oxide)-block-poly(N-isopropylacrylamide) (PEP-b-PEO-b-PNIPAm) in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide forms a thermoreversible gel network with negligible looping defects. PEP-core micelles exist at all temperatures, while cooling causes association of the PNIPAm micelle corona to form a bridging network. Small-angle x-ray scattering and dynamic light scattering were used to characterize the high-temperature micelles. These gels show enhanced mechanical properties and the ability to form gels at lower concentrations than the corresponding thermoresponsive ABA triblock copolymers.

  4. Gel electrolytes based on poly(acrylonitrile)/sulpholane with hybrid TiO2/SiO2 filler for advanced lithium polymer batteries

    International Nuclear Information System (INIS)

    Highlights: • Paper describes properties of gel electrolyte based on PAN with TMS and TiO2-SiO2. • The TiO2-SiO2 oxide composite was precipitated in the emulsion system and used as the fillers. • The capacity of the graphite anode depends on the current rate and the amount of TiO2-SiO2. • For PE3 electrolyte was obtained practical capacity more than 90% of the theoretical capacity. - Abstract: This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes. Hybrid TiO2-SiO2 ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion batteries based on polyacrylonitrile (PAN) membranes. The powders and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte uptake and electrochemical characteristics in Li-ion cells

  5. Radiation-induced degradation of polysaccharide sodium alginate

    International Nuclear Information System (INIS)

    The radiation-induced degradation of sodium alginate by 60Co γ-rays was investigated in air at ambient temperature, and the change in their molecular weights was measured by multi-angle laser light scattering detector equipped with gel permeation chromatography (MALLS/GPC). The molecular weight of sodium alginate decreases with the increase of absorbed dose in the range of 0-60 kGy at the dose rate of 80 Gy/ min. The dispersion of molecular weight distribution of sodium alginate becomes narrow along with the absorbed dose. The weight-average molecular weight (Mw) changes from 321596.5 to 10024 when the absorbed dose increases from o kGy to 60 kGy. It is found that the degraded sodium alginate with molecular weight peak of 6000 is 83.22% of cumulative weight fraction. Anyway, the sodium alginate may have comprehensive application in the fields of agriculture, medicine and cosmetology as it can be absorbed well by biological tissue, if its weight-average molecular weight is below 10000. It is also found that new components will be contained in the products of sodium alginate degraded by irradiation. The further study dealing with the checking the biological safety and purification shall be performed. (authors)

  6. Preparation methods of alginate nanoparticles

    NARCIS (Netherlands)

    Paques, J.P.; Linden, van der E.; Rijn, van C.J.M.; Sagis, L.M.C.

    2014-01-01

    This article reviews available methods for the formation of alginate nano-aggregates, nanocapsules and nanospheres. Primarily, alginate nanoparticles are being prepared by two methods. In the “complexation method”, complex formation on the interface of an oil droplet is used to form alginate nanocap

  7. A novel application of normoxic polymer gel dosimeters for near real-time dose measurement using cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tung-Hsin; Tsai, Chia-Jung [Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taiwan (China); Zhang, Geoffrey [Department of Radiation Oncology, Moffitt Cancer Center, FL (United States); Yu, Chun-Yen; Liang, Ji-An [Department of Radiation Oncology, China Medical University Hospital, Taiwan (China); Wu, Jay [Department of Radiological Technology, Central Taiwan University of Science and Technology, Taiwan (China); Lee, Jason JS. [Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taiwan (China); Ho, Yung-Jen, E-mail: d9600@mail.cmuh.org.tw [Department of Biomedical Imaging and Radiological Science, China Medical University, Taiwan (China); Huang, Tzung-Chi, E-mail: tzungchi.huang@mail.cmu.edu.tw [Department of Biomedical Imaging and Radiological Science, China Medical University, Taiwan (China)

    2011-05-15

    The aim of this study is to evaluate the feasibility of using cone-beam CT system as a near real-time measurement device in dose estimation with normoxic polymer gel dosimetry (MAG). Each vial was filled with MAG gel and irradiated with uniform doses of 0-10 Gy to generate dose response curves. After irradiation, a cone-beam CT was used to perform the 3D dose measurement. In this study, two groups of gel samples were irradiated and measured in two ways for comparison: near real-time measurement, in which the gel phantom was read right after the irradiation, and delayed measurement, in which the measurement was performed 30 min, 4 h and 1 day after the irradiation for the gel phantom to be exposed to oxygen. All groups were also performed with and without a full bowtie filter to estimate the influence of a full bowtie filter to dose response. The linear dose response curves with and without a full bowtie filter for the four different CT imaging times were within a range 0.044-0.049{Delta}N{sub CT} cGy{sup -1} and 0.061-0.063{Delta}N{sub CT} cGy{sup -1}, respectively, with no significant difference at different imaging times. Nevertheless, dose response curves with the full bowtie filter were higher than those without, with p-value <0.05 for all the different imaging times tested. Normoxic polymer gel dosimetry combined with cone-beam CT provides a useful method for near real-time dose measurement.

  8. Rapidly in situ forming biodegradable hydrogels by combining alginate and hydroxyapatite nanocrystal

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The in situ forming biodegradable polymer scaffolds are important biomaterials for tissue engineering and drug delivery.Hydrogels derived from natural proteins and polysaccharides are ideal tissue engineering scaffolds since they resemble the extracellular matrices of the tissue comprising various amino acids and sugar based macromolecules.This work presented an injectable system from partially oxidized alginate and hydroxyapatite(HAP) nanocrystal for tissue engineering and drug delivery applications.In situ release of calcium cations from HAP nanocrystal was adopted through lowering the pH with slow hydrolysis of D-glucono-δ-lactone(GDL) and homogeneous alginate gels were formulated as scaffolds with defined dimensions.The gelation time could be controlled to be in 10-15 min.The SEM observations confirmed the porous 3D hydrogel structure with interconnected pores ranging from 20 to 300 μm and the HAP particles dispersed in the scaffolds uniformly.The potential applications such as tissue engineering scaffold and injectable drug delivery system were demonstrated by subcutaneous implant test in test rats.

  9. Super-capacitive electro-chemical performance of polymer blend gel polymer electrolyte (GPE) in carbon-based electrical double-layer capacitors

    International Nuclear Information System (INIS)

    This study reports on the fabrication and comparative performance characteristics of a symmetrical electrical double-layer capacitor (EDLC) employed gel polymer electrolyte (GPE) assembled between carbon based electrodes. Three cells, A, B and C were fabricated using different composition of active materials (activated or porous carbon), binder (PVdF-HFP) and conductivity enhancer (super-P). The configuration of cell A: 0.9 porous carbon/0.1 PVdF-HFP, cell B: 0.45 activated carbon/0.45 porous carbon/0.1 PVdF-HFP and cell C: 0.8 activated carbon/0.1 super-P/0.1 PVdF-HFP. The GPE, comprising a poly(vinyl pyrrolidone) (PVP)/poly(vinylidene fluoride co-hexafluoroproplyne) (PVdF-HFP) blend complexed with magnesium triflate, Mg(CF3SO3)2, was prepared by the solution casting technique at 60 °C. The physico-chemical properties of the GPEs were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The ionic conductivity at the ambient temperature of the GPE is 2.16 × 10−4 S cm−1 at 7.5 wt.% of Mg(CF3SO3)2 with a ∼2.6 V electro-chemical stability window. At the 1000th cycle, the specific capacitance, Cs of cell A is 89 F g−1 while cell B and C are 63 and 49 F g−1. Cell A shows excellent long-term cyclic stability (less than a 5% decrease in specific capacitance after 1000 cycles). The best operating voltage for cell A is 1.6 V with the specific capacitance 106 F g−1 after 500 cycles

  10. A Gel-Polymer Sn-C/LiMn0.5Fe0.5PO4 Battery Using a Fluorine-Free Salt.

    Science.gov (United States)

    Di Lecce, Daniele; Fasciani, Chiara; Scrosati, Bruno; Hassoun, Jusef

    2015-09-30

    Safety and environmental issues, because of the contemporary use of common liquid electrolytes, fluorinated salts, and LiCoO2-based cathodes in commercial Li-ion batteries, might be efficiently mitigated by employing alternative gel-polymer battery configurations and new electrode materials. Herein we study a lithium-ion polymer cell formed by combining a LiMn0.5Fe0.5PO4 olivine cathode, prepared by simple solvothermal pathway, a nanostructured Sn-C anode, and a LiBOB-containing PVdF-based gel electrolyte. The polymer electrolyte, here analyzed in terms of electrochemical stability by impedance spectroscopy (EIS) and voltammetry, reveals full compatibility for cell application. The LiBOB electrolyte salt and the electrochemically delithiaded Mn0.5Fe0.5PO4 have a higher thermal stability compared to conventional LiPF6 and Li0.5CoO2, as confirmed by thermogravimetric analysis (TGA) and by galvanostatic cycling at high temperature. LiMn0.5Fe0.5PO4 and Sn-C, showing in lithium half-cell a capacity of about 120 and 350 mAh g(-1), respectively, within the gelled electrolyte configuration are combined in a full Li-ion polymer battery delivering a stable capacity of about 110 mAh g(-1), with working voltage ranging from 2.8 to 3.6 V. PMID:26348604

  11. Fabrication of TiO{sub 2} {mu}-donuts by sol-gel spin coating using a polymer mask

    Energy Technology Data Exchange (ETDEWEB)

    Saleema, N. [Atmospheric Icing Engineering of Power Networks (CIGELE) and Atmospheric Icing of Power Network Equipment (INGIVRE), Universite du Quebec a Chicoutimi, 555 Blvd. University, Quebec, G7H 2B1 (Canada)], E-mail: snoormoh@uqac.ca; Farzaneh, M. [Atmospheric Icing Engineering of Power Networks (CIGELE) and Atmospheric Icing of Power Network Equipment (INGIVRE), Universite du Quebec a Chicoutimi, 555 Blvd. University, Quebec, G7H 2B1 (Canada); Paynter, R.W. [INRS, Centre Energie Materiaux Telecommunications, 1650 Boulevard Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada)

    2009-03-15

    TiO{sub 2} {mu}-donuts have been fabricated on glass and silicon substrates using polymer masks in combination with a sol-gel technique. Cylindrical poly(methyl methacrylate) (PMMA) nanopillars have been created using a composite polymer of polystyrene (PS) and PMMA followed by careful removal of the PS. Atomic force microscopy (AFM) analyses show that the height and diameter of the PMMA cylinders used as the mask are 440 {+-} 5 nm and 2.1 {+-} 0.2 {mu}m, respectively. The cylindrical PMMA nanopillars have been coated with the sol of the TiO{sub 2} precursor by a spin coating technique and annealed in air at elevated temperature to remove the PMMA mask. Removal of the PMMA mask has resulted in the formation of well ordered {mu}-donuts of TiO{sub 2} on silicon surfaces. The interior and exterior heights of the TiO{sub 2} {mu}-donuts are found to be 373 {+-} 152 nm and 457 {+-} 136 nm, respectively; and the interior and exterior diameters of the TiO{sub 2} {mu}-donuts are found to be 1.33 {+-} 0.63 {mu}m and 2.82 {+-} 0.50 {mu}m, respectively. X-ray photoelectron spectroscopy (XPS) spectra of the TiO{sub 2} {mu}-donuts as well as the smooth TiO{sub 2} thin film showed signals from Ti and O confirming the presence of TiO{sub 2} with Ti 2p{sub 3/2} and O 1s peaks at 458.8 eV and 530.4 eV, respectively. The O 1s peak of the TiO{sub 2} {mu}-donuts shows another peak at binding energy 532.0 eV due to SiO{sub 2}, as during annealing, the PMMA evaporates and the Si substrate is exposed. The X-ray diffractometer (XRD) pattern of the smooth TiO{sub 2} thin film indicates that the anatase phase is present, with the characteristic peaks observed at 2{theta} values of 25.4{sup o}, 37.4{sup o}, and 48{sup o} corresponding to (1 0 1), (0 0 4), and (2 0 0) planes, respectively. UV-vis absorption spectra of TiO{sub 2} {mu}-donuts on glass showed an unusual absorption of light in the visible region at {approx}524 nm in addition to the usual UV absorption at {approx}337 nm.

  12. Transport Phenomena in Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2016-05-01

    Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

  13. Radiation protection on polysaccharide solutions and gels

    International Nuclear Information System (INIS)

    The effects of ionizing radiation on solutions of (1) sodium alginate, (2) alginate gels (wet and dry), (3) xanthan glum, (4), locust bean gum (LBG) and (5) carboxymethyl cellulose (CMC), have been investigated. Problems arise in the radiation sterilization of these gums (either as a solution or gel) due to reduction in their viscosity and the gel strength, caused by the high doses (25kGy) commonly used for the purpose of sterilization. The alginates used here were manugel DMB, manugel DPB and manucol DMF. The irradiations were carried out using 60Co-γ-source and the gels and solutions were analysed by measurement of their apparent viscosities using a Brookfield viscometer L.V.T. (author)

  14. SU-E-T-70: Commissioning a Multislice CT Scanner for X-Ray CT Polymer Gel Dosimetry

    International Nuclear Information System (INIS)

    Purpose: To commission a multislice computed tomography (CT) scanner for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD). Methods: Commissioning was performed for a 16-slice CT scanner using images acquired through a 1L cylinder filled with water. Additional images were collected using a single slice machine for comparison purposes. The variability in CT number associated with the anode heel effect was evaluated and used to define a new slice-by-slice background image subtraction technique. Image quality was assessed for the multislice system by comparing image noise and uniformity to that of the single slice machine. The consistency in CT number across slices acquired simultaneously using the multislice detector array was also evaluated. Finally, the variability in CT number due to increasing x-ray tube load was measured for the multislice scanner and compared to the tube load effects observed on the single slice machine. Results: Slice-by-slice background subtraction effectively removes the variability in CT number across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image quality for the multislice machine was found to be comparable to that of the single slice scanner. Further study showed CT number was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thickness examined. In addition, the multislice system was found to eliminate variations in CT number due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to imaging a large volume using a single slice scanner. Conclusion: A multislice CT scanner has been commissioning for CT PGD, allowing images of an entire dose distribution to be acquired in a matter of minutes. Funding support provided by the Natural Sciences and Engineering

  15. Evaluation of boronate-containing polymer brushes and gels as substrates for carbohydrate-mediated adhesion and cultivation of animal cells.

    Science.gov (United States)

    Ivanov, Alexander E; Kumar, Ashok; Nilsang, Suthasinee; Aguilar, Maria-Rosa; Mikhalovska, Lyubov I; Savina, Irina N; Nilsson, Lars; Scheblykin, Ivan G; Kuzimenkova, Marina V; Galaev, Igor Yu

    2010-02-01

    Boronate-containing thin polyacrylamide gels (B-Gel), polymer brushes (B-Brush) and chemisorbed organosilane layers (B-COSL) were prepared on the surface of glass slides and studied as substrates for carbohydrate-mediated cell adhesion. B-COSL- and B-Brush-modified glass samples exhibited multiple submicron structures densely and irregularly distributed on the glass surface, as found by scanning electron microscopy and atomic force microscopy. B-Gel was ca. 0.1 mm thick and contained pores with effective size of 1-2 microm in the middle and of 5-20 microm on the edges of the gel sample as found by confocal laser scanning microscopy. Evidence for the presence of phenylboronic acid in the samples was given by time-of-flight secondary ion mass-spectrometry (ToF SIMS), contact angle measurements performed in the presence of fructose, and staining with Alizarin Red S dye capable of formation specific, fluorescent complexes with boronic acids. A comparative study of adhesion and cultivation of animal cells on the above substrates was carried out using murine hybridoma M2139 cell line as a model. M2139 cells adhered to the substrates in the culture medium without glucose or sodium pyruvate at pH 8.0, and then were cultivated in the same medium at pH 7.2 for 4 days. It was found that the substrates of B-Brush type were superior both regarding cell adhesion and viability of the adhered cells, among the substrates studied. MTT assay confirmed proliferation of M2139 cells on B-Brush substrates. Some cell adhesion was also registered in the macropores of B-Gel substrate. The effects of surface microstructure of the boronate-containing polymers on cell adhesion are discussed. Transparent glass substrates grafted with boronate-containing copolymers offer good prospects for cell adhesion studies and development of cell-based assays. PMID:19837569

  16. Extended release microparticle-in-gel formulation of octreotide: Effect of polymer type on acylation of peptide during in vitro release.

    Science.gov (United States)

    Vaishya, Ravi D; Mandal, Abhirup; Patel, Sulabh; Mitra, Ashim K

    2015-12-30

    Polymeric microparticles (MPs)-in-gel formulations for extended delivery of octreotide were developed. We investigated influence of polymer composition on acylation of octreotide and kinetics of release during in vitro release from biodegradable polymeric formulations. Polycaprolactone (PCL), polylactic acid (PLA), polyglycolic acid (PGA) and polyethylene glycol (PEG) based triblock (TB≈PCL10k-PEG2k-PCL10k) and pentablock (PBA≈PLA3k-PCL7k-PEG2k-PCL7k-PLA3k and PBB≈PGA3k-PCL7k-PEG2k-PCL7k-PGA3k) polymers were investigated. Octreotide was encapsulated in MPs using methanol-oil/water emulsion solvent evaporation method. The particles were characterized for size, morphology, encapsulation efficiency, drug loading and in vitro release. Release samples were subjected to HPLC analysis for quantitation and HPLC-MS analysis for identification of native and chemically modified octreotide adducts. Entrapment efficiency of methanol-oil/water method with TB, PBA and PBB polymers were 45%, 60%, and 82%, respectively. A significant fraction of released octreotide was acylated from lactide and glycolide based PBA (53%) and PBB (92%) polymers. Substantial amount of peptide was not released from PBB polymers after 330 days of incubation. Complete release of octreotide was achieved from TB polymer over a period of 3 months with minimal acylation of peptide (13%). PCL based polymers resulted in minimal acylation of peptide and hence may be suitable for extended peptide and protein delivery. Conversely, polymers having PLA and PGA blocks may not be appropriate for peptide delivery due to acylation and incomplete release.

  17. An additive manufacturing-based PCL-alginate-chondrocyte bioprinted scaffold for cartilage tissue engineering.

    Science.gov (United States)

    Kundu, Joydip; Shim, Jin-Hyung; Jang, Jinah; Kim, Sung-Won; Cho, Dong-Woo

    2015-11-01

    Regenerative medicine is targeted to improve, restore or replace damaged tissues or organs using a combination of cells, materials and growth factors. Both tissue engineering and developmental biology currently deal with the process of tissue self-assembly and extracellular matrix (ECM) deposition. In this investigation, additive manufacturing (AM) with a multihead deposition system (MHDS) was used to fabricate three-dimensional (3D) cell-printed scaffolds using layer-by-layer (LBL) deposition of polycaprolactone (PCL) and chondrocyte cell-encapsulated alginate hydrogel. Appropriate cell dispensing conditions and optimum alginate concentrations for maintaining cell viability were determined. In vitro cell-based biochemical assays were performed to determine glycosaminoglycans (GAGs), DNA and total collagen contents from different PCL-alginate gel constructs. PCL-alginate gels containing transforming growth factor-β (TGFβ) showed higher ECM formation. The 3D cell-printed scaffolds of PCL-alginate gel were implanted in the dorsal subcutaneous spaces of female nude mice. Histochemical [Alcian blue and haematoxylin and eosin (H&E) staining] and immunohistochemical (type II collagen) analyses of the retrieved implants after 4 weeks revealed enhanced cartilage tissue and type II collagen fibril formation in the PCL-alginate gel (+TGFβ) hybrid scaffold. In conclusion, we present an innovative cell-printed scaffold for cartilage regeneration fabricated by an advanced bioprinting technology. PMID:23349081

  18. Water-compatible silica sol-gel molecularly imprinted polymer as a potential delivery system for the controlled release of salicylic acid.

    Science.gov (United States)

    Li, Bin; Xu, Jingjing; Hall, Andrew J; Haupt, Karsten; Tse Sum Bui, Bernadette

    2014-09-01

    Molecularly imprinted polymers (MIPs) for salicylic acid were synthesized and evaluated in aqueous environments in the aim to apply them as drug delivery carriers. One organic MIP and one inorganic MIP based on the sol-gel process were synthesized. The organic MIP was prepared by radical polymerization using the stoichiometric functional monomer, 1-(4-vinylphenyl)-3-(3,5-bis(trifluoromethyl)phenyl)urea, which can establish strong electrostatic interactions with the -COOH of salicylic acid. The sol-gel MIP was prepared with 3-(aminopropyl)triethoxysilane and trimethoxyphenylsilane, as functional monomers and tetraethyl orthosilicate as the crosslinker. While the organic MIPs bound the target specifically in acetonitrile, they exhibited lower binding in the presence of water, although the imprinting factor increased under these conditions, due to reduced non-specific binding. The sol-gel MIP has a high specificity and capacity for the drug in ethanol, a solvent compatible with drug formulation and biomedical applications. In vitro release profiles of the polymers in water were evaluated, and the results were modelled by Fick's law of diffusion and the power law. Analysis shows that the release mechanism was predominantly diffusion-controlled.

  19. Synthesis of Pb-alginate imprinted polymer and processing of trace heavy metals%Pb-海藻酸钠印迹聚合物合成及其对痕量重金属的处理

    Institute of Scientific and Technical Information of China (English)

    赵彬; 江元汝

    2011-01-01

    针对水中痕量重金属的选择性处理,以Pb(Ⅱ)离子为模板,海藻酸钠为功能单体,合成Pb-海藻酸钠印迹聚合物(Pb-SAIIP),研究了Pb-SAIIP对水中痕量Pb的吸附性能.结果表明,Pb-SAIIP对多种重金属水环境中的低浓度铅具有选择吸附作用,吸附40 min时吸附率达为98%;Pb-SMIP具有较好的循环使用寿命,吸附洗脱循环6次后,对水体中重金属Pb仍然具有较高的吸附容量,吸附衰减率为1%.%The selective treatment to trace heavy metals, Pb(Ⅱ) ion as template, sodium alginate as functional monomer,were used to synthesize Pb-rimprinted polymers ( Pb-SAIIP) . The research was about the trace Pb2+ adsorption of Pb-SAIIP. The results showed that Pb-SAIIP had a choice of adsorption with low concentration of lead in heavy-metals water environment. The adsorption rate after adsorbing 40 min was 98% ,Pb-SAIIP had a good cycle life. After cycled adsorbing and eluting of heavy metals in water 6 times,it still had a high adsorption capacity of Pbz+ ,with the adsorption decay rate of 1%.

  20. Digital microfluidic three-dimensional cell culture and chemical screening platform using alginate hydrogels.

    Science.gov (United States)

    George, Subin M; Moon, Hyejin

    2015-03-01

    Electro wetting-on-dielectric (EWOD) digital microfluidics (DMF) can be used to develop improved chemical screening platforms using 3-dimensional (3D) cell culture. Alginate hydrogels are one common method by which a 3D cell culture environment is created. This paper presents a study of alginate gelation on EWOD DMF and investigates designs to obtain uniform alginate hydrogels that can be repeatedly addressed by any desired liquids. A design which allows for gels to be retained in place during liquid delivery and removal without using any physical barriers or hydrophilic patterning of substrates is presented. A proof of concept screening platform is demonstrated by examining the effects of different concentrations of a test chemical on 3D cells in alginate hydrogels. In addition, the temporal effects of the various chemical concentrations on different hydrogel posts are demonstrated, thereby establishing the benefits of an EWOD DMF 3D cell culture and chemical screening platform using alginate hydrogels. PMID:25945142

  1. Physical and chemical characterization of titanium-alginate samples for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Morani, L.M.; Ribeiro, A.A.; Oliveira, M.V. de; Dantas, F.M.L., E-mail: marize.varella@int.gov.b [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil); Leao, M.H.M.R. [Universidade Federal do Rio de Janeiro (EQ/UFRJ), RJ (Brazil). Escola de Quimica

    2010-07-01

    The sol-gel technique combined with powder metallurgy may be an alternative to produce titanium parts for bioengineering, with the advantage of eliminating the powder compaction step, which may introduce defects. The present work introduces a system consisted of titanium powder and sodium alginate suspension, which undergoes reticulation in contact with a calcium salt solution, obtaining titanium/calcium alginate hydrogel with granule morphology. The characterization of the raw materials and granules of calcium alginate and titanium/calcium alginate was performed by x-ray fluorescence spectroscopy and thermogravimetric analysis. The granules topography was analyzed by scanning electron microscopy/EDS. Titanium and sodium alginate chemical composition were adequate for use as raw materials, showing that the methodology used is suitable for processing titanium samples for further consolidation by sintering, in order to produce titanium parts. (author)

  2. Gelling process of sodium alginate with bivalent ions rich microsphere: Nature of bivalent ions

    Science.gov (United States)

    Mauri, Marco; Vicini, Silvia; Castellano, Maila

    2016-05-01

    In the paper we present a new approach for obtaining a controlled gelling process of sodium alginate, based on the quantity of bivalent ions rich alginate micro-beads added as crosslinkers. Typically, calcium ions are used in gelation of alginate solutions. In this study we present different gelling systems realized with alginate microspheres, made by electrospinning methodology, enriched with different bivalent ions (Ca2+, Ba2+ and Mg2+). The microspheres were characterized under the point of view of the morphology by OM and as the ions content. Realized gels were characterized in light of the amount of the ions added to the alginate solution, and in light of the different dimensions of the micro-beads, using rheological measurements to assess the variation in the storage modulus (G'), loss modulus (G″) and complex viscosity (η*).

  3. Microencapsulation of bull spermatozoa: Its viability in alginate-egg yolk media

    Directory of Open Access Journals (Sweden)

    Kusumaningrum DA

    2015-03-01

    Full Text Available Microencapsulation of spermatozoa is a process to entrap a number of spermatozoa in microcapsule. Alginate, as a natural polymer polysaccharide is commonly used in cell microencapsulation. Tris Yolk Citrate buffer is a good buffer for spermatozoa dilution, therefore this experiment aimed to determine optimal concentration of alginate and egg yolk to sperm quality in bull spermatozoa microencapsulation. Concentration of egg yolk and alginate in media of encapsulation were determined in applications of sperm microencapsulation. Four bulls were used as semen source and only semen with good quality were used in this study. Poolled semen was diluted using the medium to get final concentration 100 x 106 cell/ ml. The first study was conducted to determine the effect of concentration of alginate (0, 1, and 1.5% on viability of spermatozoa. The second study to determine the effect of alginate concentration, egg yolk and its interaction was done by comparing two levels of alginate (1 and 1.5% with four levels of egg yolk (5, 10, 15 and 20%. Viability of spermatozoa, motility (M, live spermatozoa (L and Intact Apical Ridge (IAR were observed at 0, 1, 2 and 3 h incubation at room temperature. Results indicated that alginate concentration increased the osmolality and viscosity but did not affect pH of the medium. The osmolality and viscosity of medium were 275, 325, 425 and 1.12, 26.62, 47.98 for concentration of alginate 0, 1 and 1.5% respectively. Percentage of motility is significantly lower (P<0.05 in alginate medium than those of control, and 1.5% alginate could produce more uniform beads. Concentration of alginate, egg yolk and its interaction did not significantly affect viability of sperm. It is concluded that the combination of 1.5% alginate with 5, 10, 15 or 20% egg yolk can be used as media for sperm encapsulation.

  4. Modeling of the reticulation kinetics of alginate/pluronic blends for biomedical applications.

    Science.gov (United States)

    Barba, Anna A; Lamberti, Gaetano; Rabbia, Luca; Grassi, Mario; Larobina, Domenico; Grassi, Gabriele

    2014-04-01

    In this work, blends of alginate/pluronic (F127) for biomedical applications were investigated. In particular, the kinetics of alginate chain reticulation by bivalent cations was studied by experimental and modeling approaches. Two kinds of sodium alginate were tested to obtain hard gel films. The thicknesses of the reticulated alginate films were measured as function of the exposure time and of the reticulating copper (Cu(2+)) solution concentration. The kinetics was described by a proper model able to reproduce the experimental data. The model parameters, evaluated based on the measurements of thicknesses as function of Cu(2+) concentration and exposure time, were further validated by comparing the prediction of the model with another set of independent measurement; here, the depletion of Cu(2+) ions in the conditioning solution above the reacting gel is measured as function of time. The tuned model could be used in the description of the future applications of the blends. PMID:24582256

  5. Alginate modification with the coupling of primary amines relevant for nerve regeneration

    OpenAIRE

    Abdoli Najmi, Maryam

    2014-01-01

    Alginate is a polysaccharide produced by brown seaweed and some bacteria which is highly demanded in biomedical researches. It can form a gel in presence of divalent cations which has many applications in cell based therapy. Alginate can be used as immobilization matrix for transplanted cells in vivo to protect the transplanted cells against host immune system. It can be modified by coupling with adhesive peptides such as RGD to improve adhesion property for cell entrapment, relevant for tiss...

  6. TRANSPLANTATION OF CRYOPRESERVED FETAL LIVER CELLS SEEDED INTO MACROPOROUS ALGINATE-GELATIN SCAFFOLDS IN RATS WITH LIVER FAILURE

    Directory of Open Access Journals (Sweden)

    D. V. Grizay

    2015-01-01

    Full Text Available Aim. To study the therapeutic potential of cryopreserved fetal liver cells seeded into macroporous alginategelatin scaffolds after implantation to omentum of rats with hepatic failure.Materials and methods.Hepatic failure was simulated by administration of 2-acetyl aminofl uorene followed partial hepatectomy. Macroporous alginate-gelatin scaffolds, seeded with allogenic cryopreserved fetal liver cells (FLCs were implanted into rat omentum. To prevent from colonization of host cells scaffolds were coated with alginate gel shell. Serum transaminase activity, levels of albumin and bilirubin as markers of hepatic function were determined during 4 weeks after failure model formation and scaffold implantation. Morphology of liver and scaffolds after implantation were examined histologically. Results. Macroporous alginate-gelatin scaffolds after implantation to healthy rats were colonized by host cells. Additional formation of alginate gel shell around scaffolds prevented the colonization. Implantation of macroporous scaffolds seeded with cryopreserved rat FLCs and additionally coated with alginate gel shell into omentum of rats with hepatic failure resulted in signifi cant improvement of hepatospecifi c parameters of the blood serum and positive changes of liver morphology. The presence of cells with their extracellular matrix within the scaffolds was confi rmed after 4 weeks post implantation.Conclusion. The data above indicate that macroporous alginate-gelatin scaffolds coated with alginate gel shell are promising cell carriers for the development of bioengineered liver equivalents.

  7. Photonic monitoring of chitosan nanostructured alginate microcapsules for drug release

    Science.gov (United States)

    Khajuria, Deepak Kumar; Konnur, Manish C.; Vasireddi, Ramakrishna; Roy Mahapatra, D.

    2015-02-01

    By using a novel microfluidic set-up for drug screening applications, this study examines delivery of a novel risedronate based drug formulation for treatment of osteoporosis that was developed to overcome the usual shortcomings of risedronate, such as its low bioavailability and adverse gastric effects. Risedronate nanoparticles were prepared using muco-adhesive polymers such as chitosan as matrix for improving the intestinal cellular absorption of risedronate and also using a gastric-resistant polymer such as sodium alginate for reducing the gastric inflammation of risedronate. The in-vitro characteristics of the alginate encapsulated chitosan nanoparticles are investigated, including their stability, muco-adhesiveness, and Caco-2 cell permeability. Fluorescent markers are tagged with the polymers and their morphology within the microcapsules is imaged at various stages of drug release.

  8. Sol-Gel Entrapped Levonorgestrel Antibodies: Activity and Structural Changes as a Function of Different Polymer Formats

    OpenAIRE

    Moran Shalev; Altstein Miriam

    2011-01-01

    The paper describes development of a sol-gel based immunoaffinity method for the steroid hormone levonorgestrel (LNG) and the effects of changes in the sol-gel matrix format on the activity of the entrapped antibodies (Abs) and on matrix structure. The best sol-gel format for Ab entrapment was found to be a tetramethoxysilane (TMOS) based matrix at a TMOS:water ratio of 1:8, containing 10% polyethylene glycol (PEG) of MW 0.4 kDa. Addition of higher percentages of PEG or a higher MW PEG did no...

  9. Cell microencapsulation with synthetic polymers.

    Science.gov (United States)

    Olabisi, Ronke M

    2015-02-01

    The encapsulation of cells into polymeric microspheres or microcapsules has permitted the transplantation of cells into human and animal subjects without the need for immunosuppressants. Cell-based therapies use donor cells to provide sustained release of a therapeutic product, such as insulin, and have shown promise in treating a variety of diseases. Immunoisolation of these cells via microencapsulation is a hotly investigated field, and the preferred material of choice has been alginate, a natural polymer derived from seaweed due to its gelling conditions. Although many natural polymers tend to gel in conditions favorable to mammalian cell encapsulation, there remain challenges such as batch to batch variability and residual components from the original source that can lead to an immune response when implanted into a recipient. Synthetic materials have the potential to avoid these issues; however, historically they have required harsh polymerization conditions that are not favorable to mammalian cells. As research into microencapsulation grows, more investigators are exploring methods to microencapsulate cells into synthetic polymers. This review describes a variety of synthetic polymers used to microencapsulate cells. PMID:24771675

  10. Alginate based hydrogel as a potential biopolymeric carrier for drug delivery and cell delivery systems: present status and applications.

    Science.gov (United States)

    Giri, Tapan Kumar; Thakur, Deepa; Alexander, Amit; Ajazuddin; Badwaik, Hemant; Tripathi, Dulal Krishna

    2012-11-01

    Alginate is a non-toxic, biocompatible and biodegradable natural polymer with a number of peculiar physicochemical properties for which it has wide applications in drug delivery and cell delivery systems. Hydrogel formation can be obtained by interactions of anionic alginates with multivalent inorganic cations by simple ionotropic gelation method. Hydrophilic polymeric network of three dimensional cross linked structures of hydrogels absorb substantial amount of water or biological fluids. Among the numerous biomaterials used for hydrogel formation alginate has been and will continue to be one of the most important biomaterial. Therefore, in view of the vast literature support, we focus in this review on alginate - based hydrogel as drug delivery and cell delivery carriers for biomedical applications. Various properties of alginates, their hydrogels and also various techniques used for preparing alginate hydrogels have been reviewed. PMID:22998675

  11. Preparation of aminated chitosan/alginate scaffold containing halloysite nanotubes with improved cell attachment.

    Science.gov (United States)

    Amir Afshar, Hamideh; Ghaee, Azadeh

    2016-10-20

    The chemical nature of biomaterials play important role in cell attachment, proliferation and migration in tissue engineering. Chitosan and alginate are biodegradable and biocompatible polymers used as scaffolds for various medical and clinical applications. Amine groups of chitosan scaffolds play an important role in cell attachment and water adsorption but also associate with alginate carboxyl groups via electrostatic interactions and hydrogen bonding, consequently the activity of amine groups in the scaffold decreases. In this study, chitosan/alginate/halloysite nanotube (HNTs) composite scaffolds were prepared using a freeze-drying method. Amine treatment on the scaffold occurred through chemical methods, which in turn caused the hydroxyl groups to be replaced with carboxyl groups in chitosan and alginate, after which a reaction between ethylenediamine, 1-ethyl-3,(3-dimethylaminopropyl) carbodiimide (EDC) and scaffold triggered the amine groups to connect to the carboxyl groups of chitosan and alginate. The chemical structure, morphology and mechanical properties of the composite scaffolds were investigated by FTIR, CHNS, SEM/EDS and compression tests. The electrostatic attraction and hydrogen bonding between chitosan, alginate and halloysite was confirmed by FTIR spectroscopy. Chitosan/alginate/halloysite scaffolds exhibit significant enhancement in compressive strength compared with chitosan/alginate scaffolds. CHNS and EDS perfectly illustrate that amine groups were effectively introduced in the aminated scaffold. The growth and cell attachment of L929 cells as well as the cytotoxicity of the scaffolds were investigated by SEM and Alamar Blue (AB). The results indicated that the aminated chitosan/alginate/halloysite scaffold has better cell growth and cell adherence in comparison to that of chitosan/alginate/halloysite samples. Aminated chitosan/alginate/halloysite composite scaffolds exhibit great potential for applications in tissue engineering, ideally in

  12. Characteristics of Immobilized Urease on Grafted Alginate Bead Systems

    Directory of Open Access Journals (Sweden)

    Enas N. Danial

    2015-04-01

    Full Text Available This study evaluated the biological importance of immobilized urease enzyme over the free urease. The support material used for urease immobilization was alginate. Generally, the immobilization of urease in alginate gel showed a marked increase in Km and Vmax. However, the immobilized urease showed higher thermal stability than that of free enzyme. The rate of thermal inactivation of the immobilized enzyme decreased due to entrapment in gel matrix. Also, the activity of the immobilized urease was more stable in retention than that of the free enzyme during the storage in solution, although the activity of the immobilized enzyme was lower in comparison with the free enzyme. A stable immobilized system and long storage life are convenient for applications that would not be feasible with a soluble enzyme system. These results highlighted the technical and biochemical benefits of immobilized urease over the free enzyme.

  13. The study of the structural properties of very low viscosity sodium alginate by small-angle neutron scattering

    Science.gov (United States)

    Badita, C. R.; Aranghel, D.; Radulescu, A.; Anitas, E. M.

    2016-03-01

    Sodium alginate is a linear polymer extract from brown algae and it is used in the biomedical, food, cosmetics and pharmaceutical industries as solution property modifiers and gelling agents. But despite the extensive studies of the alginate gelation process, still some fundamental questions remain unresolved. The fractal behavior of very low viscosity sodium alginate solutions and their influence on the critical gelation of alginate induced by Ca2+ ions were investigated using Small-Angle Neutron Scattering (SANS) measurements. SANS data are interpreted using both standard linear plots and the Beaucage model. The scattering intensity is dependent by alginate concentration and Ca2+ concentration. From a critical concentration of 1.0 % w/w our polymer swelled forming spherical structures with rough surfaces. Also the addition of the salt induces the collapse and the appearance of the aggregation and clusters formation.

  14. POLYPEPTIDE EXTRACTION FROM ALGINATE HYDROGELS in vitro AND in vivo

    Directory of Open Access Journals (Sweden)

    T. V. Shkand

    2014-06-01

    Full Text Available Dependence of rheological and diffusion properties of gels on their composition as well as desorption of active components from the resulted implants in biological objects have been studied. The work has been performed in vitro using step-wise extraction of polypeptides form the heart of newborn piglets and also in vivo by implanting the «gel-extract» complex into muscular tissue of rats. The dynamics of peptide transfer was assessed using photometric and fluorometric methods. It has been established that with the growth of alginate concentration in gel there is a transition from convective mechanism of mass transfer to molecular diffusion. The study of the dynamics of mass transfer of fluorescent protein (R-phycoerythrin has shown that peptides release from a gel into surrounding tissues for 5 hrs with the rate of 8‒9% per hours with following decrease in the extraction rate due to cross diffusion, which contributes to prolonged effect of peptides to a target organ. Thus the data presented about mass transfer in alginate gels should be taken into account when designing the compositions of «peptide-extract gels» during transplantation into biological objects.

  15. Adsorption characteristics, recognition properties, and preliminary application of nordihydroguaiaretic acid molecularly imprinted polymers prepared by sol-gel surface imprinting technology

    Science.gov (United States)

    Liao, Sen; Zhang, Wen; Long, Wei; Hou, Dan; Yang, Xuechun; Tan, Ni

    2016-02-01

    In this paper, a new core-shell composite of nordihydroguaiaretic acid (NDGA) molecularly imprinted polymers layer-coated silica gel (MIP@SiO2) was prepared through sol-gel technique and applied as a material for extraction of NDGA from Ephedra. It was synthesized using NDGA as the template molecule, γ-aminopropyltriethoxysilane (APTS) and methyltriethoxysilane (MTEOS) as the functional monomers, tetraethyl orthosilicate (TEOS) as the cross-linker and ethanol as the porogenic solvent in the surface of silica. The non-imprinted polymers layer-coated silica gel (NIP@SiO2) were prepared with the same procedure, but with the absence of template molecule. In addition, the optimum adsorption affinity occurred when the molar ratio of NDGA:APTS:MTEOS:TEOS was 1:6:2:80. The prepared MIP@SiO2 and NIP@SiO2 were analyzed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform-infrared spectroscopy (FT-IR). Their affinity properties to NDGA were evaluated through dynamic adsorption, static adsorption, and selective recognition experiments, and the results showed the saturated adsorption capacity of MIP@SiO2 could reach to 5.90 mg g-1, which was two times more than that of NIP@SiO2. High performance liquid chromatography (HPLC) was used to evaluate the extraction of NDGA from the medicinal plant ephedra by the above prepared materials, and the results indicated that the MIP@SiO2 had potential application in separation of the natural active component NDGA from medicinal plants.

  16. Design and performance of a sericin-alginate interpenetrating network hydrogel for cell and drug delivery

    OpenAIRE

    Yeshun Zhang; Jia Liu; Lei Huang; Zheng Wang; Lin Wang

    2015-01-01

    Although alginate hydrogels have been extensively studied for tissue engineering applications, their utilization is limited by poor mechanical strength, rapid drug release, and a lack of cell adhesive ability. Aiming to improve these properties, we employ the interpenetrating hydrogel design rationale. Using alginate and sericin (a natural protein with many unique properties and a major component of silkworm silk), we develop an interpenetrating polymer network (IPN) hydrogel comprising inter...

  17. Novel alginate-based nanocarriers as a strategy to include high concentrations of hydrophobic compounds in hydrogels for topical application

    Science.gov (United States)

    Nguyen, H. T. P.; Munnier, E.; Souce, M.; Perse, X.; David, S.; Bonnier, F.; Vial, F.; Yvergnaux, F.; Perrier, T.; Cohen-Jonathan, S.; Chourpa, I.

    2015-06-01

    The cutaneous penetration of hydrophobic active molecules is of foremost concern in the dermatology and cosmetic formulation fields. The poor solubility in water of those molecules limits their use in hydrophilic forms such as gels, which are favored by patients with chronic skin disease. The aim of this work is to design a novel nanocarrier of hydrophobic active molecules and to determine its potential as an ingredient of a topical form. The nanocarrier consists of an oily core surrounded by a protective shell of alginate, a natural polysaccharide isolated from brown algae. These calcium alginate-based nanocarriers (CaANCs) were prepared at room temperature and without the use of organic solvent by an accelerated nanoemulsification-polymer crosslinking method. The size (hydrodynamic diameter ˜200 nm) and surface charge (zeta potential ˜ - 30 mV) of the CaANCs are both compatible with their application on skin. CaANCs loaded with a fluorescent label were stable in model hydrophilic galenic forms under different storage conditions. Curcumin was encapsulated in CaANCs with an efficiency of ˜95%, fully retaining its antioxidant activity. The application of the curcumin-loaded CaANCs on excised human skin led to a significant accumulation of the active molecules in the upper layers of the skin, asserting the potential of these nanocarriers in active pharmaceutical and cosmetic ingredients topical delivery.

  18. Feasibility study using MRI and two optical CT scanners for readout of polymer gel and PresageTM

    Science.gov (United States)

    Svensson, H.; Skyt, P. S.; Ceberg, S.; Doran, S.; Muren, L. P.; Balling, P.; Petersen, J. B. B.; Bäck, S. Å. J.

    2013-06-01

    The aim of this study was to compare the conventional combination of three-dimensional dosimeter (nPAG gel) and readout method (MRI) with other combinations of three-dimensional dosimeters (nPAG gel/PresageTM) and readout methods (optical CT scanners). In the first experiment, the dose readout of a gel irradiated with a four field-box technique was performed with both an Octopus IQ scanner and MRI. It was seen that the MRI readout agreed slightly better to the TPS. In another experiment, a gel and a PresageTM sample were irradiated with a VMAT field and read out using MRI and a fast laser scanner, respectively. A comparison between the TPS and the volumes revealed that the MRI/gel readout had closer resemblance to the TPS than the optical CT/PresageTM readout. There are clearly potential in the evaluated optical CT scanners, but more time has to be invested in the particular scanning scenario than was possible in this study.

  19. Evaluation of an alginate-gelatine crosslinked hydrogel for bioplotting.

    Science.gov (United States)

    Zehnder, Tobias; Sarker, Bapi; Boccaccini, Aldo R; Detsch, Rainer

    2015-04-08

    Using additive manufacturing to create hydrogel scaffolds which incorporate homogeneously distributed, immobilized cells in the context of biofabrication approaches represents an emerging and expanding field in tissue engineering. Applying hydrogels for additive manufacturing must consider the material processing properties as well as their influence on the immobilized cells. In this work alginate-dialdehyde (ADA), a partially oxidized alginate, was used as a basic material to improve the physico-chemical properties of the hydrogel for cell immobilization. At first, the processing ability of the gel using a bioplotter and the compatibility of the process with MG-63 osteoblast like cells were investigated. The metabolic and mitochondrial activities increased at the beginning of the incubation period and they balanced at a relatively high level after 14-28 days of incubation. During this incubation period the release of vascular endothelial growth factor-A also increased. After 28 days of incubation the cell morphology showed a spreading morphology and cells were seen to move out of the scaffold struts covering the whole scaffold structure. The reproducible processing capability of alginate-gelatine (ADA-GEL) and the compatibility with MG-63 cells were proven, thus the ADA-GEL material is highlighted as a promising matrix for applications in biofabrication.

  20. Effect of polyacrylonitrile on triethylene glycol diacetate-2-propenoic acid butyl ester gel polymer electrolytes with interpenetrating crosslinked network for flexible lithium ion batteries

    Science.gov (United States)

    Wang, Qiujun; Song, Wei-Li; Fan, Li-Zhen; Shi, Qiao

    2015-11-01

    A new flexible gel polymer electrolytes (GPE) with interpenetrating cross-linked network is fabricated by blending long-chain polyacrylonitrile (PAN) polymer matrix and short-chain triethylene glycol diacetate-2-propenoic acid butyl ester (TEGDA-BA) framework, with the purpose of enhancing the mechanical stability of the GPE frameworks via synergistic effects of the linear polymers and crosslinked monomers. The as fabricated frameworks enable the liquid electrolytes to be firmly entrapped in the polymeric matrices, which significantly improves the mechanical bendability and interface stability of the resultant GPE. The GPE with 5 wt% PAN exhibits high ionic conductivity up to 5.9 × 10-3 S cm-1 at 25 °C with a stable electrochemical window observed (>5.0 V vs. Li/Li+). The Li|GPE|LiFePO4 half cells demonstrate remarkably stable capacity retention and rate ability during cycling tests. As expected, the LiFePO4|GPE|Li4Ti5O12 full cells also exhibit discharge capacity of 125.2 mAh g-1 coupled with high columbic efficiency greater than 98% after 100 cycles. The excellent mechanical flexibility and charge/discharge performance suggest that the GPE holds great application potential in flexible LIBs.

  1. Solid-state electric double layer capacitors fabricated with plastic crystal based flexible gel polymer electrolytes: Effective role of electrolyte anions

    Energy Technology Data Exchange (ETDEWEB)

    Suleman, Mohd; Kumar, Yogesh; Hashmi, S.A., E-mail: sahashmi@physics.du.ac.in

    2015-08-01

    Flexible gel polymer electrolyte (GPE) thick films incorporated with solutions of lithium trifluoromethanesulfonate (Li-triflate or LiTf) and lithium bis trifluoromethane-sulfonimide (LiTFSI) in a plastic crystal succinonitrile (SN), entrapped in poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP) have been prepared and characterized. The films have been used as electrolytes in the electrical double layer capacitors (EDLCs). Coconut-shell derived activated carbon with high specific surface area (∼2100 m{sup 2} g{sup −1}) and mixed (micro- and meso-) porosity has been used as EDLC electrodes. The structural, thermal, and electrochemical characterization of the GPEs have been performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), impedance measurements and cyclic voltammetry. The high ionic conductivity (∼10{sup −3} S cm{sup −1} at 25 °C), good electrochemical stability window (>4.0 V) and flexible nature of the free-standing films of GPEs show their competence in the fabrication of EDLCs. The EDLCs have been tested using electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge studies. The EDLCs using LiTf based electrolyte have been found to give higher values of specific capacitance, specific energy, power density (240–280 F g{sup −1}, ∼39 Wh kg{sup −1} and ∼19 kW kg{sup −1}, respectively) than the EDLC cell with LiTFSI based gel electrolyte. EDLCs have been found to show stable performance for ∼10{sup 4} charge–discharge cycles. The comparative studies indicate the effective role of electrolyte anions on the capacitive performance of the solid-state EDLCs. - Graphical abstract: Display Omitted - Highlights: • Flexible EDLCs with succinonitrile based gel electrolyte membranes are reported. • Anionic size of salts in gel electrolytes plays important role on capacitive performance. • Li-triflate incorporated gel electrolyte shows better

  2. Solid-state electric double layer capacitors fabricated with plastic crystal based flexible gel polymer electrolytes: Effective role of electrolyte anions

    International Nuclear Information System (INIS)

    Flexible gel polymer electrolyte (GPE) thick films incorporated with solutions of lithium trifluoromethanesulfonate (Li-triflate or LiTf) and lithium bis trifluoromethane-sulfonimide (LiTFSI) in a plastic crystal succinonitrile (SN), entrapped in poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP) have been prepared and characterized. The films have been used as electrolytes in the electrical double layer capacitors (EDLCs). Coconut-shell derived activated carbon with high specific surface area (∼2100 m2 g−1) and mixed (micro- and meso-) porosity has been used as EDLC electrodes. The structural, thermal, and electrochemical characterization of the GPEs have been performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), impedance measurements and cyclic voltammetry. The high ionic conductivity (∼10−3 S cm−1 at 25 °C), good electrochemical stability window (>4.0 V) and flexible nature of the free-standing films of GPEs show their competence in the fabrication of EDLCs. The EDLCs have been tested using electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge studies. The EDLCs using LiTf based electrolyte have been found to give higher values of specific capacitance, specific energy, power density (240–280 F g−1, ∼39 Wh kg−1 and ∼19 kW kg−1, respectively) than the EDLC cell with LiTFSI based gel electrolyte. EDLCs have been found to show stable performance for ∼104 charge–discharge cycles. The comparative studies indicate the effective role of electrolyte anions on the capacitive performance of the solid-state EDLCs. - Graphical abstract: Display Omitted - Highlights: • Flexible EDLCs with succinonitrile based gel electrolyte membranes are reported. • Anionic size of salts in gel electrolytes plays important role on capacitive performance. • Li-triflate incorporated gel electrolyte shows better performance over LiTFSI-based gel. • Highest

  3. Protein composition of wheat gluten polymer fractions determined by quantitative two-dimensional gel electrophoresis and tandem mass spectrometry

    Science.gov (United States)

    Flour proteins from the US bread wheat Butte 86 were extracted in 0.5% SDS using a two-step procedure with and without sonication and further separated by size exclusion chromatography into monomeric and polymeric fractions. Proteins in each fraction were analyzed by quantitative two-dimensional gel...

  4. 骨髓间充质干细胞、肌样细胞藻酸钙复合凝胶在压力性尿失禁大鼠尿道周围的成肌效应研究%The effects of the gel compound from bone marrow mesenchymal stem cells and muscle-like cells/calcium alginate on myoblast formation around urethra in rats of stress urinary incontinence

    Institute of Scientific and Technical Information of China (English)

    杜小文; 吴慧玲; 朱永锋; 胡俊彪; 金范; 吕蕊萍; 徐剑炜; 孙思; 王皓羽

    2012-01-01

    目的 探索骨髓间充质干细胞(bone marrow mesenchymal stem cell,BMSC)藻酸钙复合凝胶与经5-氮杂胞苷诱导的肌样细胞藻酸钙复合凝胶在压力性尿失禁(stress urinary incontinence,SUI)大鼠尿道周围的成肌效应.方法 SD大鼠BMSC体外分离、培养、鉴定;用5-氮杂胞苷诱导生成肌样细胞;2%藻酸钠与1%氯化钙溶液以5∶1体积比配制藻酸钙凝胶,分别与BMSC和肌样细胞复合用于微量注射.72只6周龄雌性SD大鼠建立SUI模型后分为BMSC凝胶组、肌样细胞凝胶组、单纯凝胶组和空白对照4组,每组再分为3小组,于膀胱颈尿道移行部黏膜下肌层注射相应的复合凝胶.4周、8周时取各组大鼠尿道横截面进行HE染色、荧光示踪照相以及结蛋白、α-横纹肌动蛋白(α-SMA)染色检查. 结果 获得的BMSC第3代细胞表面细胞因子抗体CD29阳性率为89.4%、CD34为3.3%、CD45为2.5%、CD105为46.0%,荧光示踪照相见第3代培养细胞表达强绿色荧光.BMSC凝胶组和肌样细胞凝胶组4周、8周时,凝胶边缘血管长入并逐渐增多,荧光示踪BMSC聚集于新生血管周围,肌样细胞呈长梭形样生长,结蛋白、d-SMA明显阳性表达. 结论 BMSC、肌样细胞藻酸钙复合凝胶在大鼠SUI实验模型的微环境中具有向肌细胞分化的潜力.BMSC直接体内微环境诱导分化与5-氮杂胞苷体外诱导形成肌样细胞后植入体内微环境继续分化,短期结果无明显差异.%Objective To explore the effects of myoblast formation around the urethra of stress urinary incontinence (SUI) rats after treated with bone marrow mesenchymal stem cells(BMSCs) or musclelike cells/calcium alginate composite gel injection therapy. Methods Isolation,cultivation and identification of Sprague-Dawley rat bone marrow mesenchymal stem cell were performed.5-azacytidine was introduced to induce muscle-like cells.Calcium alginate gel was initially prepared by 2% sodium alginate and 1

  5. SU-E-CAMPUS-T-05: Validation of High-Resolution 3D Patient QA for Proton Pencil Beam Scanning and IMPT by Polymer Gel Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cardin, A; Avery, S; Ding, X; Kassaee, A; Lin, L [University of Pennsylvania, Philadelphia, PA (United States); Maryanski, M [MGS Research, Inc., Madison, CT (United States)

    2014-06-15

    Purpose: Validation of high-resolution 3D patient QA for proton pencil beam scanning and IMPT by polymer gel dosimetry. Methods: Four BANG3Pro polymer gel dosimeters (manufactured by MGS Research Inc, Madison, CT) were used for patient QA at the Robert's Proton Therapy Center (RPTC, Philadelphia, PA). All dosimeters were sealed in identical thin-wall Pyrex glass spheres. Each dosimeter contained a set of markers for 3D registration purposes. The dosimeters were mounted in a consistent and reproducible manner using a custom build holder. Two proton pencil beam scanning plans were designed using Varian Eclipse™ treatment planning system: 1) A two-field intensity modulated proton therapy (IMPT) plan and 2) one single field uniform dose (SFUD) plan. The IMPT fields were evaluated as a composite plan and individual fields, the SFUD plan was delivered as a single field plan.Laser CT scanning was performed using the manufacturer's OCTOPUS-IQ axial transmission laser CT scanner using a 1 mm slice thickness. 3D registration, analysis, and OD/cm to absorbed dose calibrations were perfomed using DICOM RT-Dose and CT files, and software developed by the manufacturer. 3D delta index, a metric equivalent to the gamma tool, was used for dose comparison. Results: Very good agreement with single IMPT fields and with SFUD was obtained. Composite IMPT fields had a less satisfactory agreement. The single fields had 3D delta index passing rates (3% dose difference, 3 mm DTA) of 98.98% and 94.91%. The composite 3D delta index passing rate was 80.80%. The SFUD passing rate was 93.77%. Required shifts of the dose distributions were less than 4 mm. Conclusion: A formulation of the BANG3Pro polymer gel dosimeter, suitable for 3D QA of proton patient plans is established and validated. Likewise, the mailed QA analysis service provided by the manufacturer is a practical option when required resources are unavailable. We fully disclose that the subject of this research regards a

  6. Manipulation and Characterization of Alginate Exo polysaccharides produced by Azotobacter Vinelandii

    International Nuclear Information System (INIS)

    Exo polysaccharides (EPS) have been found in a wide range of applications in food industry and in the biomedical field. In the present study, the effect of nutritional factors (carbon and nitrogen sources) and gamma irradiations on alginate production by Azotobacter vinelandii was investigated. To understand the direct and indirect relations among these variables, a two way factorial design experiment was set up. At low concentration of carbon source (≤ 20 g/l), the alginate yield was influenced by the type of nitrogen substrate and C/N ratio, whereas the role of these factors on alginate production was minimized at high concentration of carbon source (> 20 g/l). Batch fermentation of alginate exo polysaccharides was manipulated by maintaining the ph value of the cultures at 7 along the incubation period and reducing the agitation speed to 100 rpm after 24 h at the time of inoculation. This process succeeded to increase the alginate yield exponentially with time by 50%. Exposing A. vinelandii cells to gamma irradiation at dose level 0.5 kGy decreased their activity to synthesis alginate by 44%. The produced alginate was characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and differential scanning calorimeter (DSC).

  7. Improved Mobility Control for Carbon Dioxide (CO{sub 2}) Enhanced Oil Recovery Using Silica-Polymer-Initiator (SPI) Gels

    Energy Technology Data Exchange (ETDEWEB)

    Oglesby, Kenneth

    2014-01-31

    SPI gels are multi-component silicate based gels for improving (areal and vertical) conformance in oilfield enhanced recovery operations, including water-floods and carbon dioxide (CO{sub 2}) floods, as well as other applications. SPI mixtures are like-water when pumped, but form light up to very thick, paste-like gels in contact with CO{sub 2}. When formed they are 3 to 10 times stronger than any gelled polyacrylamide gel now available, however, they are not as strong as cement or epoxy, allowing them to be washed / jetted out of the wellbore without drilling. This DOE funded project allowed 8 SPI field treatments to be performed in 6 wells (5 injection wells and 1 production well) in 2 different fields with different operators, in 2 different basins (Gulf Coast and Permian) and in 2 different rock types (sandstone and dolomite). Field A was in a central Mississippi sandstone that injected CO{sub 2} as an immiscible process. Field B was in the west Texas San Andres dolomite formation with a mature water-alternating-gas miscible CO{sub 2} flood. Field A treatments are now over 1 year old while Field B treatments have only 4 months data available under variable WAG conditions. Both fields had other operational events and well work occurring before/ during / after the treatments making definitive evaluation difficult. Laboratory static beaker and dynamic sand pack tests were performed with Ottawa sand and both fields’ core material, brines and crude oils to improve SPI chemistry, optimize SPI formulations, ensure SPI mix compatibility with field rocks and fluids, optimize SPI treatment field treatment volumes and methods, and ensure that strong gels set in the reservoir. Field quality control procedures were designed and utilized. Pre-treatment well (surface) injectivities ranged from 0.39 to 7.9 MMCF/psi. The SPI treatment volumes ranged from 20.7 cubic meters (m{sup 3}, 5460 gallons/ 130 bbls) to 691 m{sup 3} (182,658 gallons/ 4349 bbls). Various size and types

  8. Synthesis and characterization of chitosan impregnated calcium alginate beads for removal of uranium from aquatic stream

    International Nuclear Information System (INIS)

    The present study was conducted to study the feasibility of chitosan impregnated calcium alginate beads (Cal-Alg-Chi) to sorb the excess uranium from the aquatic stream. Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). The optimal composition of calcium alginate chitosan beads is 4 % (wt/vol) alginate gel having 5% loading of chitosan. The nature and morphology of pure and uranium sorbed calcium alginate chitosan beads were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), and attenuated total reflectance Fourier transform infrared spectroscopy (ATRFTIR). The results of batch sorption experiments suggest that Cal-Alg-Chi beads are very effective for removal of uranium in the pH range of 2.0-5.0 and sorption is more than 80 % in the concentration range of 1-100 mgL-1

  9. Interplay between flow and diffusion in capillary alginate hydrogels.

    Science.gov (United States)

    Schuster, Erich; Sott, Kristin; Ström, Anna; Altskär, Annika; Smisdom, Nick; Gebäck, Tobias; Lorén, Niklas; Hermansson, Anne-Marie

    2016-05-01

    Alginate gels with naturally occurring macroscopic capillaries have been used as a model system to study the interplay between laminar flow and diffusion of nanometer-sized solutes in real time. Calcium alginate gels that contain homogeneously distributed parallel-aligned capillary structures were formed by external addition of crosslinking ions to an alginate sol. The effects of different flow rates (0, 1, 10, 50 and 100 μl min(-1)) and three different probes (fluorescein, 10 kDa and 500 kDa fluorescein isothiocyanate-dextran) on the diffusion rates of the solutes across the capillary wall and in the bulk gel in between the capillaries were investigated using confocal laser scanning microscopy. The flow in the capillaries was produced using a syringe pump that was connected to the capillaries via a tube. Transmission electron microscopy revealed an open aggregated structure close to the capillary wall, followed by an aligned network layer and the isotropic network of the bulk gel. The most pronounced effect was observed for the 1 nm-diameter fluorescein probe, for which an increase in flow rate increased the mobility of the probe in the gel. Fluorescence recovery after photobleaching confirmed increased mobility close to the channel, with increasing flow rate. Mobility maps derived using raster image correlation spectroscopy showed that the layer with the lowest mobility corresponded to the anisotropic layer of ordered network chains. The combination of microscopy techniques used in the present study elucidates the flow and diffusion behaviors visually, qualitatively and quantitatively, and represents a promising tool for future studies of mass transport in non-equilibrium systems.

  10. SU-E-T-102: Determination of Dose Distributions and Water-Equivalence of MAGIC-F Polymer Gel for 60Co and 192Ir Brachytherapy Sources

    Energy Technology Data Exchange (ETDEWEB)

    Quevedo, A; Nicolucci, P [University of Sao Paulo, Ribeirao Preto, SP (Brazil)

    2014-06-01

    Purpose: Analyse the water-equivalence of MAGIC-f polymer gel for {sup 60}Co and {sup 192}Ir clinical brachytherapy sources, through dose distributions simulated with PENELOPE Monte Carlo code. Methods: The real geometry of {sup 60} (BEBIG, modelo Co0.A86) and {sup 192}192Ir (Varian, model GammaMed Plus) clinical brachytherapy sources were modelled on PENELOPE Monte Carlo simulation code. The most probable emission lines of photons were used for both sources: 17 emission lines for {sup 192}Ir and 12 lines for {sup 60}. The dose distributions were obtained in a cubic water or gel homogeneous phantom (30 × 30 × 30 cm{sup 3}), with the source positioned in the middle of the phantom. In all cases the number of simulation showers remained constant at 10{sup 9} particles. A specific material for gel was constructed in PENELOPE using weight fraction components of MAGIC-f: wH = 0,1062, wC = 0,0751, wN = 0,0139, wO = 0,8021, wS = 2,58×10{sup −6} e wCu = 5,08 × 10{sup −6}. The voxel size in the dose distributions was 0.6 mm. Dose distribution maps on the longitudinal and radial direction through the centre of the source were used to analyse the water-equivalence of MAGIC-f. Results: For the {sup 60} source, the maximum diferences in relative doses obtained in the gel and water were 0,65% and 1,90%, for radial and longitudinal direction, respectively. For {sup 192}Ir, the maximum difereces in relative doses were 0,30% and 1,05%, for radial and longitudinal direction, respectively. The materials equivalence can also be verified through the effective atomic number and density of each material: Zef-MAGIC-f = 7,07 e .MAGIC-f = 1,060 g/cm{sup 3} and Zef-water = 7,22. Conclusion: The results showed that MAGIC-f is water equivalent, consequently being suitable to simulate soft tissue, for Cobalt and Iridium energies. Hence, gel can be used as a dosimeter in clinical applications. Further investigation to its use in a clinical protocol is needed.

  11. DMA and Conductivity Studies in PVA:NH4SCN:DMSO:MWNT Nanocomposite Polymer Dried Gel Electrolytes

    Directory of Open Access Journals (Sweden)

    S. L. Agrawal

    2015-01-01

    Full Text Available This paper deals with findings on dynamic mechanical analysis (DMA and ion-conduction behavior of MWNTs (multiwall carbon nanotubes doped PVA:NH4SCN:DMSO dried gel electrolyte system prepared for four filler concentrations (2, 4, 6 & 8 wt% by solution cast technique. XRD measurements reveal enhancement in amorphous behavior of composite gel electrolyte upon incorporation of filler particles. Better mechanical stability is noticed in the composite system upon dispersal of MWNT along with presence of dynamic Tg during DMA measurements. Enhancement in ionic conductivity has been noticed with an optimum value of 4.5 × 10−3 Scm−1 for 6 wt% MWNTs filled composite electrolyte. Composite system exhibits combination of Arrhenius and Vogel-Tammam-Fulcher (VTF behavior in temperature dependent conductivity study. The a.c. conductivity response seems to follow universal power law.

  12. An application of optical coherence tomography and a smart polymer gel to construct an enzyme-free sugar sensor

    Science.gov (United States)

    Ouiganon, Sirirat; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya; Buranachai, Chittanon

    2016-06-01

    This work reports a novel enzyme-free sugar sensor development based on optical coherence tomography (OCT) and a 3-acrylamidophenylboronic acid-acrylamide copolymer gel that swells when it binds sugar molecules. Utilizing OCT to measure the gel swelling in the presence of glucose and fructose, selected as model targets, the sensor provided a linear range of 2.5-20.0 mM for glucose and 0.01-0.20 mM for fructose detections with a good sensitivity for both sugars under optimal conditions. With some further improvements, the sensor could be used in harsh conditions that are not suitable for enzyme-based sugar sensors and for highly visible light-absorbing solutions.

  13. Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples

    International Nuclear Information System (INIS)

    In this research, we used a 135 MeV/nucleon carbon-ion beam to irradiate a biological sample composed of fresh chicken meat and bones, which was placed in front of a PAGAT gel dosimeter, and compared the measured and simulated transverse-relaxation-rate (R2) distributions in the gel dosimeter. We experimentally measured the three-dimensional R2 distribution, which records the dose induced by particles penetrating the sample, by using magnetic resonance imaging. The obtained R2 distribution reflected the heterogeneity of the biological sample. We also conducted Monte Carlo simulations using the PHITS code by reconstructing the elemental composition of the biological sample from its computed tomography images while taking into account the dependence of the gel response on the linear energy transfer. The simulation reproduced the experimental distal edge structure of the R2 distribution with an accuracy under about 2 mm, which is approximately the same as the voxel size currently used in treatment planning. (paper)

  14. Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples

    Science.gov (United States)

    Furuta, T.; Maeyama, T.; Ishikawa, K. L.; Fukunishi, N.; Fukasaku, K.; Takagi, S.; Noda, S.; Himeno, R.; Hayashi, S.

    2015-08-01

    In this research, we used a 135 MeV/nucleon carbon-ion beam to irradiate a biological sample composed of fresh chicken meat and bones, which was placed in front of a PAGAT gel dosimeter, and compared the measured and simulated transverse-relaxation-rate (R2) distributions in the gel dosimeter. We experimentally measured the three-dimensional R2 distribution, which records the dose induced by particles penetrating the sample, by using magnetic resonance imaging. The obtained R2 distribution reflected the heterogeneity of the biological sample. We also conducted Monte Carlo simulations using the PHITS code by reconstructing the elemental composition of the biological sample from its computed tomography images while taking into account the dependence of the gel response on the linear energy transfer. The simulation reproduced the experimental distal edge structure of the R2 distribution with an accuracy under about 2 mm, which is approximately the same as the voxel size currently used in treatment planning.

  15. Three-dimensional verification of intracranial target point deviation using MRI-Based polymer-gel dosimetry for conventional and fractionated stereotactic radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Nam; Suh, Tae Suk [The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of); Lee, Dong Joon [Ilsanpaik Hospital, College of Medicine, Inje University, Goyang (Korea, Republic of)

    2011-09-15

    Conventional (SRS) and fractionated (FSRS) stereotactic radiosurgery necessarily require stringent overall target point accuracy and precision. We determine three-dimensional intracranial target point deviations (TPDs) in a whole treatment procedure using magnetic resonance image (MRI)-based polymer-gel dosimetry, and suggest a technique for overall system tests. TPDs were measured using a custom-made head phantom and gel dosimetry. We calculated TPDs using a treatment planning system. Then, we compared TPDs using mid bi-plane and three-dimensional volume methods with spherical and elliptical targets to determine their inherent analysis errors; finally, we analyzed regional TPDs using the latter method. Average and maximum additive errors for ellipses were 0.62 and 0.69 mm, respectively. Total displacements were 0.92 {+-} 0.25 and 0.77 {+-} 0.15 mm for virtual SRS and FSRS, respectively. Average TPDtotal at peripheral regions was greater than that at central regions for both. Overall system accuracy was similar to that reported previously. Our technique could be used as an overall system accuracy test that considers the real radiation field shape.

  16. Enhanced aggregation of alginate-coated iron oxide (hematite) nanoparticles in the presence of calcium, strontium, and barium cations.

    Science.gov (United States)

    Chen, Kai Loon; Mylon, Steven E; Elimelech, Menachem

    2007-05-22

    Early-stage aggregation kinetics studies of alginate-coated hematite nanoparticles in solutions containing alkaline-earth metal cations revealed enhanced aggregation rates in the presence of Ca2+, Sr2+, and Ba2+, but not with Mg2+. Transmission electron microscopy (TEM) imaging of the aggregates provided evidence that alginate gel formation was essential for enhanced aggregation to occur. Dynamic light scattering (DLS) aggregation results clearly indicated that a much lower concentration of Ba2+ compared to Ca2+ and Sr2+ was required to achieve a similar degree of enhanced aggregation in each system. To elucidate the relationship between the alginate's affinities for divalent cations and the enhanced aggregation of the alginate-coated hematite nanoparticles, atomic force microscopy (AFM) was employed to probe the interaction forces between alginate-coated hematite surfaces under the solution chemistries used for the aggregation study. Maximum adhesion forces, maximum pull-off distances, and the work of adhesion were used as indicators to gauge the alginate's affinity for the divalent cations and the resulting attractive interactions between alginate-coated hematite nanoparticles. The results showed that alginate had higher affinity for Ba2+ than either Sr2+ or Ca2+. This same trend was consistent with the cation concentrations required for comparable enhanced aggregation kinetics, suggesting that the rate of alginate gel formation controls the enhanced aggregation kinetics. An aggregation mechanism incorporating the gelation of alginate is proposed to explain the accelerated aggregate growth in the presence of Ca2+, Sr2+, and Ba2+. PMID:17469860

  17. Three-dimensional bioprinting of complex cell laden alginate hydrogel structures.

    Science.gov (United States)

    Tabriz, Atabak Ghanizadeh; Hermida, Miguel A; Leslie, Nicholas R; Shu, Wenmiao

    2015-12-21

    Different bioprinting techniques have been used to produce cell-laden alginate hydrogel structures, however these approaches have been limited to 2D or simple three-dimension (3D) structures. In this study, a new extrusion based bioprinting technique was developed to produce more complex alginate hydrogel structures. This was achieved by dividing the alginate hydrogel cross-linking process into three stages: primary calcium ion cross-linking for printability of the gel, secondary calcium cross-linking for rigidity of the alginate hydrogel immediately after printing and tertiary barium ion cross-linking for long-term stability of the alginate hydrogel in culture medium. Simple 3D structures including tubes were first printed to ensure the feasibility of the bioprinting technique and then complex 3D structures such as branched vascular structures were successfully printed. The static stiffness of the alginate hydrogel after printing was 20.18 ± 1.62 KPa which was rigid enough to sustain the integrity of the complex 3D alginate hydrogel structure during the printing. The addition of 60 mM barium chloride was found to significantly extend the stability of the cross-linked alginate hydrogel from 3 d to beyond 11 d without compromising the cellular viability. The results based on cell bioprinting suggested that viability of U87-MG cells was 93 ± 0.9% immediately after bioprinting and cell viability maintained above 88% ± 4.3% in the alginate hydrogel over the period of 11 d.

  18. Deterioration of polyamino acid-coated alginate microcapsules in vivo.

    Science.gov (United States)

    van Raamsdonk, J M; Cornelius, R M; Brash, J L; Chang, P L

    2002-01-01

    of calcium-mediated ionic cross-linking of the guluronic acid polymers in the alginate. These destructive forces may be slightly mitigated by using poly-L-arginine instead of poly-L-lysine for coating and by implanting in a subcutaneous instead of an intraperitoneal site. However, the long-term stability of such devices may require significant improvements in the microcapsule polymer chemistry to withstand such biological impediments. PMID:12463508

  19. Preparation and characterization of. beta. -D-glucosidase immobilized in calcium alginate

    Energy Technology Data Exchange (ETDEWEB)

    Krasniak, S. R.; Smith, R. D.

    1982-01-01

    Enzymatic hydrolysis of biomass to produce glucose may become feasible if an inexpensive method to reuse the enzyme can be found. This study investigated one such method whereby ..beta..-D-glucosidase (E.C. 3.2.1.21) was immobilized in calcium alginate gel spheres, which were shown to catalyze the hydrolysis of cellobiose to glucose. There was a loss of 49% of the enzyme from the alginate slurry during gelation. After gelation, in the stable gel spheres, there was a 37% retention of the enzyme activity that was actually immobilized. The reason for the loss in activity was investigated and may be caused by inhibition of the enzyme within the sphere by the calcium cations and the alginate anions also present. Mass transfer effects were minimal in this system and were not responsible for the activity loss.

  20. A honeycomb composite of mollusca shell matrix and calcium alginate.

    Science.gov (United States)

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering.

  1. Structural basis for alginate secretion across the bacterial outer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, J.C.; Robinson, H.; Hay, I. D.; Li, C.; Eckford, P. D. W.; Amaya, M. F.; Wood, L. F.; Ohman, D. E.; Bear, C. E.; Rehm, B. H.; Howell, P. L.

    2011-08-09

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  2. Structural Basis for Alginate Secretion Across the Bacterial Outer Membrane

    Energy Technology Data Exchange (ETDEWEB)

    J Whitney; I Hay; C Li; P Eckford; H Robinson; M Amaya; L Wood; D Ohman; C Bear; et al.

    2011-12-31

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  3. Physicochemical characterization and biocompatibility of alginate-polycation microcapsules designed for islet transplantation

    Science.gov (United States)

    Tam, Susan Kimberly

    Microencapsulation represents a method for immunoprotecting transplanted therapeutic cells or tissues from graft rejection using a physical barrier. This approach is advantageous in that it eliminates the need to induce long-term immunosuppression and allows the option of transplanting non-cadaveric cell sources, such as animal cells and stem cell-derived tissues. The microcapsules that we have investigated are designed to immunoprotect islets of Langerhans (i.e. clusters of insulin-secreting cells), with the goal of treating insulin-dependent diabetes. With the aid of techniques for physicochemical analysis, this research focused on understanding which properties of the microcapsule are the most important for determining its biocompatibility. The objective of this work was to elucidate correlations between the chemical make-up, physicochemical properties, and in vivo biocompatibility of alginate-based microcapsules. Our approach was based on the hypothesis that the immune response to the microcapsules is governed by, and can therefore be controlled by, specific physicochemical properties of the microcapsule and its material components. The experimental work was divided into five phases, each associated with a specific aim : (1) To prove that immunoglobulins adsorb to the surface of alginate-polycation microcapsules, and to correlate this adsorption with the microcapsule chemistry. (2) To test interlaboratory reproducibility in making biocompatible microcapsules, and evaluate the suitability of our materials and fabrication protocols for subsequent studies. (3) To determine which physicochemical properties of alginates affect the in vivo biocompatibility of their gels. (4) To determine which physiochemical properties of alginate-polycation microcapsules are most important for determining their in vivo biocompatibility (5) To determine whether a modestly immunogenic membrane hinders or helps the ability of the microcapsule to immunoprotect islet xenografts in

  4. Physicochemical characterization and biocompatibility of alginate-polycation microcapsules designed for islet transplantation

    Science.gov (United States)

    Tam, Susan Kimberly

    Microencapsulation represents a method for immunoprotecting transplanted therapeutic cells or tissues from graft rejection using a physical barrier. This approach is advantageous in that it eliminates the need to induce long-term immunosuppression and allows the option of transplanting non-cadaveric cell sources, such as animal cells and stem cell-derived tissues. The microcapsules that we have investigated are designed to immunoprotect islets of Langerhans (i.e. clusters of insulin-secreting cells), with the goal of treating insulin-dependent diabetes. With the aid of techniques for physicochemical analysis, this research focused on understanding which properties of the microcapsule are the most important for determining its biocompatibility. The objective of this work was to elucidate correlations between the chemical make-up, physicochemical properties, and in vivo biocompatibility of alginate-based microcapsules. Our approach was based on the hypothesis that the immune response to the microcapsules is governed by, and can therefore be controlled by, specific physicochemical properties of the microcapsule and its material components. The experimental work was divided into five phases, each associated with a specific aim : (1) To prove that immunoglobulins adsorb to the surface of alginate-polycation microcapsules, and to correlate this adsorption with the microcapsule chemistry. (2) To test interlaboratory reproducibility in making biocompatible microcapsules, and evaluate the suitability of our materials and fabrication protocols for subsequent studies. (3) To determine which physicochemical properties of alginates affect the in vivo biocompatibility of their gels. (4) To determine which physiochemical properties of alginate-polycation microcapsules are most important for determining their in vivo biocompatibility (5) To determine whether a modestly immunogenic membrane hinders or helps the ability of the microcapsule to immunoprotect islet xenografts in

  5. Immobilization of Brassica oleracea Chlorophyllase 1 (BoCLH1 and Candida rugosa Lipase (CRL in Magnetic Alginate Beads: An Enzymatic Evaluation in the Corresponding Proteins

    Directory of Open Access Journals (Sweden)

    Chih-Hui Yang

    2014-08-01

    Full Text Available Enzymes have a wide variety of applications in diverse biotechnological fields, and the immobilization of enzymes plays a key role in academic research or industrialization due to the stabilization and recyclability it confers. In this study, we immobilized the Brassica oleracea chlorophyllase 1 (BoCLH1 or Candida rugosa lipase (CRL in magnetic iron oxide nanoparticles-loaded alginate composite beads. The catalytic activity and specific activity of the BoCLH1 and CRL entrapped in magnetic alginate composite beads were evaluated. Results show that the activity of immobilized BoCLH1 in magnetic alginate composite beads (3.36 ± 0.469 U/g gel was higher than that of immobilized BoCLH1 in alginate beads (2.96 ± 0.264 U/g gel. In addition, the specific activity of BoCLH1 beads (10.90 ± 1.521 U/mg protein was higher than that immobilized BoCLH1 in alginate beads (8.52 ± 0.758 U/mg protein. In contrast, the immobilized CRL in magnetic alginate composite beads exhibited a lower enzyme activity (11.81 ± 0.618 than CRL immobilized in alginate beads (94.83 ± 7.929, and the specific activity of immobilized CRL entrapped in magnetic alginate composite beads (1.99 ± 0.104 was lower than immobilized lipase in alginate beads (15.01 ± 1.255. A study of the degradation of magnetic alginate composite beads immersed in acidic solution (pH 3 shows that the magnetic alginate composite beads remain intact in acidic solution for at least 6 h, indicating the maintenance of the enzyme catalytic effect in low-pH environment. Finally, the enzyme immobilized magnetic alginate composite beads could be collected by an external magnet and reused for at least six cycles.

  6. Effect of Thiolated Polymers to Textural and Mucoadhesive Properties of Vaginal Gel Formulations Prepared with Polycarbophil and Chitosan

    OpenAIRE

    Cevher, Erdal; Sensoy, Demet; Taha, Mohamed A. M.; Araman, Ahmet

    2008-01-01

    The aim of this study was to design and evaluate of mucoadhesive gel formulations for the vaginal application of clomiphene citrate (CLM) for local treatment of human papilloma virus (HPV) infections. Chitosan (CHI) and polycarbophil (PC) were covalently modified using the thioglycolic acid and L-cysteine, respectively. The formation of thiol conjugates of chitosan (CHI-TG) and polycarbophil (PC-CYS) were confirmed by FT-IR analysis and PC-CYS and CHI-TG were found to have 148.42 ± 4.16 and 4...

  7. CONFORMANCE IMPROVEMENT USING GELS

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Seright

    2003-09-01

    flow capacity of fractures (with widths from 1 to 4 mm) during brine and oil flow after placement. Regardless of gel age before placement, very little gel washed out from the fractures during brine or oil flow. However, increased brine or oil flow rate and cyclic injection of oil and water significantly decreased the level of permeability reduction. A particular need exists for gels that can plug large apertures (e.g., wide fractures and vugs). Improved mechanical strength and stability were demonstrated (in 1- to 4-mm-wide fractures) for a gel that contained a combination of high- and low-molecular weight polymers. This gel reduced the flow capacity of 2- and 4-mm-wide fractures by 260,000. In a 1-mm-wide fracture, it withstood 26 psi/ft without allowing any brine flow through the fracture. Cr(III)-acetate-HPAM gels exhibited disproportionate permeability reduction in fractures. The effect was most pronounced when the gel was placed as gelant or partially formed gels. The effect occurred to a modest extent with concentrated gels and with gels that were ''fully formed'' when placed. The effect was not evident in tubes. We explored swelling polymers for plugging fractures. Polymer suspensions were quickly prepared and injected. In concept, the partially dissolved polymer would lodge and swell to plug the fracture. For three types of swelling polymers, behavior was promising. However, additional development is needed before their performance will be superior to that of conventional gels.

  8. in Situ Formation of a Biocatalytic Alginate Membrane by Enhanced Concentration Polarization

    DEFF Research Database (Denmark)

    Marpani, Fauziah; Luo, Jianquan; Mateiu, Ramona Valentina;

    2015-01-01

    immobilized enzyme loadings, which would benefit from the decreased flux in terms of increased enzyme/substrate contact time. The study was performed in a sequential fashion: first, the most suitable types of alginate able to induce a very thin, sustainable gel layer by pressure-driven membrane filtration...

  9. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong-Kyun; Volosin, Alex

    2016-06-14

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite material can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.

  10. Metal selectivity of Sargassum spp. and their alginates in relation to their alpha-L-guluronic acid content and conformation.

    Science.gov (United States)

    Davis, Thomas A; Llanes, Francisco; Volesky, Bohumil; Mucci, Alfonso

    2003-01-15

    The discovery of a consistent and unusual enrichment in homopolymeric alpha-L-guluronic acid G-blocks in alginates extracted from a suite of Sargassum brown algae is described in this study. 1H NMR spectroscopy was used to characterize these alginates which display homopolymeric guluronic acid block (G-block) frequency values (F(GG)) between 0.37 and 0.81. The presence of these G-blocks results in an enhanced selectivity for cadmium or calcium relative to monovalent ions such as sodium and the proton as well as smaller divalent ions such as magnesium. Results of competitive exchange experiments for the Cd-Ca-alginate system yield selectivity coefficient, K*(Cd)Ca, values between 0.43 +/- 0.10 and 1.32 +/- 0.02 for a range in F(GG) of 0.23 to 0.81. In contrast to the Cd-Ca-alginate system, the Mg-Ca-alginate and Mg-Cd-alginate systems yielded maximum values of K*(Mg)Ca (18.0 +/- 1.4) and K*(Mg)Cd (16.0 +/- 0.9) for the alginates extracted from Sargassum fluitans (F(GG) = 0.81; Cuba) and Sargassum thunbergii (F(GG) = 0.75; Korea), respectively. Selectivity studies with mixed-metal pair alginate systems highlight the importance of the specific macromolecular conformation of the alginate polymer in determining metal binding behavior in multiple-metal systems. Furthermore, they demonstrate the importance of the conformation of the alginate as it occurs within the tissue of Sargassum in determining the metal binding behavior of this algal biosorbent. The unique composition of the alginates present in species of Sargassum may represent a distinct advantage over other brown algal species when considering their implementation for the strategic removal of toxic heavy metals from contaminated and industrial wastewaters. PMID:12564896

  11. Drug carrier systems based on collagen-alginate composite structures for improving the performance of GDNF-secreting HEK293 cells.

    Science.gov (United States)

    Lee, M; Lo, A C; Cheung, P T; Wong, D; Chan, B P

    2009-02-01

    Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor. Development of drug delivery technologies facilitating controlled release of GDNF is critical to applying GDNF in treating neurodegenerative diseases. We previously developed 3D collagen microspheres and demonstrated enhanced GDNF secretion after encapsulation of HEK293 cells, which were transduced to overexpress GDNF in these microspheres. However, the entrapped HEK293 cells were able to migrate out of the collagen microspheres, making it undesirable for clinical applications. In this report, we investigate two new carrier designs, namely collagen-alginate composite gel and collagen microspheres embedded in alginate gel in preventing cell leakage, maintaining cell growth and controlling GDNF secretion in the HEK293 cells. We demonstrated that inclusion of alginate gel in both designs is efficient in preventing cell leakage to the surrounding yet permitting the GDNF secretion, although the cellular growth rate is reduced in an alginate concentration dependent manner. Differential patterns of GDNF secretion in the two designs were demonstrated. The collagen-alginate composite gel maintains a more or less constant GDNF secretion over time while the collagen microspheres embedded in alginate gel continue to increase the secretion level of GDNF over time. This study contributes towards the development of cell-based GDNF delivery devices for the future therapeutics of neurodegenerative diseases. PMID:19059641

  12. Novel copper (II) alginate hydrogels and their potential for use as anti-bacterial wound dressings.

    Science.gov (United States)

    Klinkajon, Wimonwan; Supaphol, Pitt

    2014-08-01

    The incorporation of a metal ion, with antimicrobial activity, into an alginate dressing is an attractive approach to minimize infection in a wound. In this work, copper (II) cross-linked alginate hydrogels were successfully prepared using a two-step cross-linking procedure. In the first step, solid alginate films were prepared using a solvent-casting method from soft gels of alginate solutions that had been lightly cross-linked using a copper (II) (Cu(2+)) sulfate solution. In the second step, the films were further cross-linked in a corresponding Cu(2+) sulfate solution using a dipping method to further improve their dimensional stability. Alginate solution (at 2%w/v) and Cu(2+) sulfate solution (at 2%w/v) in acetate buffer at a low pH provided soft films with excellent swelling behavior. An increase in either Cu(2+) ion concentration or cross-linking time led to hydrogels with more densely-cross-linked networks that limited water absorption. The hydrogels clearly showed antibacterial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Streptococcus pyogenes, which was proportional to the Cu(2+) ion concentration. Blood coagulation studies showed that the tested copper (II) cross-linked alginate hydrogels had a tendency to coagulate fibrin, and possibly had an effect on pro-thrombotic coagulation and platelet activation. Conclusively, the prepared films are likely candidates as antibacterial wound dressings.

  13. Influence of amino acids, buffers, and ph on the γ-irradiation-induced degradation of alginates.

    Science.gov (United States)

    Ulset, Ann-Sissel T; Mori, Hideki; Dalheim, Marianne Ø; Hara, Masayuki; Christensen, Bjørn E

    2014-12-01

    Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates' material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy. PMID:25412478

  14. Novel copper (II) alginate hydrogels and their potential for use as anti-bacterial wound dressings

    International Nuclear Information System (INIS)

    The incorporation of a metal ion, with antimicrobial activity, into an alginate dressing is an attractive approach to minimize infection in a wound. In this work, copper (II) cross-linked alginate hydrogels were successfully prepared using a two-step cross-linking procedure. In the first step, solid alginate films were prepared using a solvent-casting method from soft gels of alginate solutions that had been lightly cross-linked using a copper (II) (Cu2+) sulfate solution. In the second step, the films were further cross-linked in a corresponding Cu2+ sulfate solution using a dipping method to further improve their dimensional stability. Alginate solution (at 2%w/v) and Cu2+ sulfate solution (at 2%w/v) in acetate buffer at a low pH provided soft films with excellent swelling behavior. An increase in either Cu2+ ion concentration or cross-linking time led to hydrogels with more densely-cross-linked networks that limited water absorption. The hydrogels clearly showed antibacterial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Streptococcus pyogenes, which was proportional to the Cu2+ ion concentration. Blood coagulation studies showed that the tested copper (II) cross-linked alginate hydrogels had a tendency to coagulate fibrin, and possibly had an effect on pro-thrombotic coagulation and platelet activation. Conclusively, the prepared films are likely candidates as antibacterial wound dressings. (paper)

  15. Auger electron and X-ray photoelectron spectroscopic study of the biocorrosion of copper by alginic acid polysaccharide

    Science.gov (United States)

    Jolley, John G.; Geesey, Gill G.; Hankins, Michael R.; Wright, Randy B.; Wichlacz, Paul L.

    1989-08-01

    Thin films (3.4 nm) of copper on germanium substrates were exposed to 2% alginic acid polysaccharide aqueous solution. Pre- and post-exposure characterization were done by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that some of the copper was oxidized by the alginic acid solution. Some of the copper was removed from the Cu/Ge interface and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the alginic acid polysaccharide.

  16. Effects of alginate hydrogel cross-linking density on mechanical and biological behaviors for tissue engineering.

    Science.gov (United States)

    Jang, Jinah; Seol, Young-Joon; Kim, Hyeon Ji; Kundu, Joydip; Kim, Sung Won; Cho, Dong-Woo

    2014-09-01

    An effective cross-linking of alginate gel was made through reaction with calcium carbonate (CaCO3). We used human chondrocytes as a model cell to study the effects of cross-linking density. Three different pore size ranges of cross-linked alginate hydrogels were fabricated. The morphological, mechanical, and rheological properties of various alginate hydrogels were characterized and responses of biosynthesis of cells encapsulated in each gel to the variation in cross-linking density were investigated. Desired outer shape of structure was maintained when the alginate solution was cross-linked with the applied method. The properties of alginate hydrogel could be tailored through applying various concentrations of CaCO3. The rate of synthesized GAGs and collagens was significantly higher in human chondrocytes encapsulated in the smaller pore structure than that in the larger pore structure. The expression of chondrogenic markers, including collagen type II and aggrecan, was enhanced in the smaller pore structure. It was found that proper structural morphology is a critical factor to enhance the performance and tissue regeneration.

  17. Efficiency enhancement in dye sensitized solar cells using gel polymer electrolytes based on a tetrahexylammonium iodide and MgI2 binary iodide system.

    Science.gov (United States)

    Bandara, T M W J; Dissanayake, M A K L; Jayasundara, W J M J S R; Albinsson, I; Mellander, B-E

    2012-06-28

    Quasi-solid-state dye-sensitized solar cells have drawn the attention of scientists and technologists as a potential candidate to supplement future energy needs. The conduction of iodide ions in quasi-solid-state polymer electrolytes and the performance of dye sensitized solar cells containing such electrolytes can be enhanced by incorporating iodides having appropriate cations. Gel-type electrolytes, based on PAN host polymers and mixture of salts tetrahexylammonium iodide (Hex4N(+)I(-)) and MgI2, were prepared by incorporating ethylene carbonate and propylene carbonate as plasticizers. The salt composition in the binary mixture was varied in order to optimize the performance of solar cells. The electrolyte containing 120% Hex4N(+)I(-) with respect to weight of PAN and without MgI2 showed the highest conductivity out of the compositions studied, 2.5 × 10(-3) S cm(-1) at 25 °C, and a glass transition at -102.4 °C. However, the electrolyte containing 100% Hex4N(+)I(-) and 20% MgI2 showed the best solar cell performance highlighting the influence of the cation on the performance of the cell. The predominantly ionic behaviour of the electrolytes was established from the dc polarization data and all the electrolytes exhibit iodide ion transport. Seven different solar cells were fabricated employing different electrolyte compositions. The best cell using the electrolyte with 100% Hex4N(+)I(-) and 20% MgI2 with respect to PAN weight showed 3.5% energy conversion efficiency and 8.6 mA cm(-2) short circuit current density.

  18. Azithromycin blocks quorum sensing and alginate polymer formation and increases the sensitivity to serum and stationary growth phase killing of P. aeruginosa and attenuates chronic P. aeruginosa lung infection in Cftr -/--mice

    DEFF Research Database (Denmark)

    Hoffmann, N.; Lee, Bao le ri; Hentzer, Morten;

    2007-01-01

    The consequences of O-acetylated alginate-producing Pseudomonas aeruginosa biofilms in the lungs of chronically infected cystic fibrosis (CF) patients are tolerance to both antibiotic treatments and effects on the innate and the adaptive defense mechanisms. In clinical trials, azithromycin (AZM......, whereas cells in the exponential phase did not. Interestingly, AZM-treated P. aeruginosa lasI mutants appeared to be particularly resistant to serum, whereas bacteria with a functional QS system did not. We show in a CF mouse model of chronic P. aeruginosa lung infection that AZM treatment results...

  19. Current-voltage characterization of Au contact on sol-gel ZnO films with and without conducting polymer

    International Nuclear Information System (INIS)

    This study investigates the current density-voltage (J-V) characteristics of Au/n-type ZnO and Au/polyaniline (PANI)/n-type ZnO devices. ZnO films were prepared by the sol-gel method. For Au/n-type ZnO devices, native defects and impurities resident within the ZnO depletion region contribute to barrier thinning of, carrier hopping across, and tunneling through the Schottky barrier. This leads to the formation of nonalloyed ohmic contacts. However, rectifying junctions were formed on n-type ZnO by employing the simple technique of spin-coating PANI to act as the electron-blocking layer. Our present results suggest that the ZnO depletion region at the PANI/n-type ZnO interface is not the origin of the rectifying behavior of Au/PANI/n-type ZnO contact. In addition, the presence of the built-in potential of Au/PANI/n-type ZnO devices could result in the shift of the J-V curve toward negative voltage. Excellent agreement between simulated and measured data was obtained when the built-in potential was taken into account in the J-V relationship.

  20. Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods.

    Science.gov (United States)

    González Ocampo, Jazmín I; Escobar Sierra, Diana M; Ossa Orozco, Claudia P

    2016-03-01

    A combination of gel-casting and polymeric foam infiltration methods is used in this study to prepare porous bodies of hydroxyapatite (HA), to provide a better control over the microstructures of samples. These scaffolds were prepared by impregnating a body of porous polyurethane foam with slurry containing HA powder, and using a percentage of solids between 40% and 50% w/v, and three different types of monomers to provide a better performance. X-Ray Diffraction (XRD), and Fourier Transformed Infrared (FTIR) and Scanning Electron Microscopy (SEM) were employed to evaluate both the powder hydroxyapatite and the scaffolds obtained. In addition, porosity and interconnectivity measurements were taken in accordance with the international norm. Bioactivity was checked using immersion tests in Simulated Body Fluids (SBF). After the sintering process of the porous bodies, the XRD results showed peaks characteristic of a pure and crystalline HA (JCPDS 9-432) as a single phase. SEM images indicate open and interconnected pores inside the material, with pore sizes between 50 and 600 μm. Also, SEM images demonstrate the relatively good bioactivity of the HA scaffolds after immersion in SBF. All results for the porous HA bodies suggest that these materials have great potential for use in tissue engineering. PMID:26966570

  1. Immobilization of Electroporated Cells for Fabrication of Cellular Biosensors: Physiological Effects of the Shape of Calcium Alginate Matrices and Foetal Calf Serum

    OpenAIRE

    Nikos Katsanakis; Andreas Katsivelis; Spiridon Kintzios

    2009-01-01

    In order to investigate the physiological effect of transfected cell immobilization in calcium alginate gels, we immobilized electroporated Vero cells in gels shaped either as spherical beads or as thin membrane layers. In addition, we investigated whether serum addition had a positive effect on cell proliferation and viability in either gel configuration. The gels were stored for four weeks in a medium supplemented or not with 20% (v/v) foetal calf serum. Throughout a culture period of four ...

  2. Radiation Modification of Some Natural Polymers and Their Potential Applications

    International Nuclear Information System (INIS)

    (PAAm) which is one of the most popular polymers used to reduce water runoff and increase infiltration rates in field agricultural applications. There are different methods to improve water holding capacity of PAAm among of them; adjusting the density of its crosslinking network structure. Radiation technique is promising for preparation of hydrogels because a polymer in aqueous solution or in the water swollen state readily undergoes crosslinking on irradiation to yield a gel-like material. Irradiation dose can control the crosslinking yield of polymer. Addition of few amount of degraded natural polymer during the irradiation processing of PAAm can also reduce the hydrogel network structural density and influences its water holding capacity. Moreover, the low molecular weight natural polymer like alginate or chitosan incorporated in PAAm hydrogel help in promoting the plant growth when such hydrogels used as water supplied soil conditioner. In this connection, the crosslinked copolymers of γ-rays degraded alginate, chitosan or both of them with PAAm were prepared using ionizing radiation. The preparation conditions of the polyacrylamide/alginate (PAAm/Alg), polyacrylamide/chitosan (PAAm/CS) and polyacrylamide/alginate/chitosan (PAAm/Alg/CS) crosslinked hydrogels, such as the effect of the irradiation dose and the copolymer composition on the matrix gel content and water absorbency will be studied. The effect of different types of cations or fertilizers or buffers of different pH's on water absorbency of prepared hydrogels will be investigated. The possible use of such copolymer hydrogels in the field of agriculture for some plants will be investigated.

  3. Osteogenic Differentiation of Human Mesenchymal Stem Cells in Mineralized Alginate Matrices

    Science.gov (United States)

    Westhrin, Marita; Xie, Minli; Olderøy, Magnus Ø.; Sikorski, Pawel

    2015-01-01

    Mineralized biomaterials are promising for use in bone tissue engineering. Culturing osteogenic cells in such materials will potentially generate biological bone grafts that may even further augment bone healing. Here, we studied osteogenic differentiation of human mesenchymal stem cells (MSC) in an alginate hydrogel system where the cells were co-immobilized with alkaline phosphatase (ALP) for gradual mineralization of the microenvironment. MSC were embedded in unmodified alginate beads and alginate beads mineralized with ALP to generate a polymer/hydroxyapatite scaffold mimicking the composition of bone. The initial scaffold mineralization induced further mineralization of the beads with nanosized particles, and scanning electron micrographs demonstrated presence of collagen in the mineralized and unmineralized alginate beads cultured in osteogenic medium. Cells in both types of beads sustained high viability and metabolic activity for the duration of the study (21 days) as evaluated by live/dead staining and alamar blue assay. MSC in beads induced to differentiate in osteogenic direction expressed higher mRNA levels of osteoblast-specific genes (RUNX2, COL1AI, SP7, BGLAP) than MSC in traditional cell cultures. Furthermore, cells differentiated in beads expressed both sclerostin (SOST) and dental matrix protein-1 (DMP1), markers for late osteoblasts/osteocytes. In conclusion, Both ALP-modified and unmodified alginate beads provide an environment that enhance osteogenic differentiation compared with traditional 2D culture. Also, the ALP-modified alginate beads showed profound mineralization and thus have the potential to serve as a bone substitute in tissue engineering. PMID:25769043

  4. Osteogenic differentiation of human mesenchymal stem cells in mineralized alginate matrices.

    Directory of Open Access Journals (Sweden)

    Marita Westhrin

    Full Text Available Mineralized biomaterials are promising for use in bone tissue engineering. Culturing osteogenic cells in such materials will potentially generate biological bone grafts that may even further augment bone healing. Here, we studied osteogenic differentiation of human mesenchymal stem cells (MSC in an alginate hydrogel system where the cells were co-immobilized with alkaline phosphatase (ALP for gradual mineralization of the microenvironment. MSC were embedded in unmodified alginate beads and alginate beads mineralized with ALP to generate a polymer/hydroxyapatite scaffold mimicking the composition of bone. The initial scaffold mineralization induced further mineralization of the beads with nanosized particles, and scanning electron micrographs demonstrated presence of collagen in the mineralized and unmineralized alginate beads cultured in osteogenic medium. Cells in both types of beads sustained high viability and metabolic activity for the duration of the study (21 days as evaluated by live/dead staining and alamar blue assay. MSC in beads induced to differentiate in osteogenic direction expressed higher mRNA levels of osteoblast-specific genes (RUNX2, COL1AI, SP7, BGLAP than MSC in traditional cell cultures. Furthermore, cells differentiated in beads expressed both sclerostin (SOST and dental matrix protein-1 (DMP1, markers for late osteoblasts/osteocytes. In conclusion, Both ALP-modified and unmodified alginate beads provide an environment that enhance osteogenic differentiation compared with traditional 2D culture. Also, the ALP-modified alginate beads showed profound mineralization and thus have the potential to serve as a bone substitute in tissue engineering.

  5. In vitro fermentation of alginate and its derivatives by human gut microbiota.

    Science.gov (United States)

    Li, Miaomiao; Li, Guangsheng; Shang, Qingsen; Chen, Xiuxia; Liu, Wei; Pi, Xiong'e; Zhu, Liying; Yin, Yeshi; Yu, Guangli; Wang, Xin

    2016-06-01

    Alginate (Alg) has a long history as a food ingredient in East Asia. However, the human gut microbes responsible for the degradation of alginate and its derivatives have not been fully understood yet. Here, we report that alginate and the low molecular polymer derivatives of mannuronic acid oligosaccharides (MO) and guluronic acid oligosaccharides (GO) can be completely degraded and utilized at various rates by fecal microbiota obtained from six Chinese individuals. However, the derivative of propylene glycol alginate sodium sulfate (PSS) was not hydrolyzed. The bacteria having a pronounced ability to degrade Alg, MO and GO were isolated from human fecal samples and were identified as Bacteroides ovatus, Bacteroides xylanisolvens, and Bacteroides thetaiotaomicron. Alg, MO and GO can increase the production level of short chain fatty acids (SCFA), but GO generates the highest level of SCFA. Our data suggest that alginate and its derivatives could be degraded by specific bacteria in the human gut, providing the basis for the impacts of alginate and its derivates as special food additives on human health. PMID:26891629

  6. In vitro fermentation of alginate and its derivatives by human gut microbiota.

    Science.gov (United States)

    Li, Miaomiao; Li, Guangsheng; Shang, Qingsen; Chen, Xiuxia; Liu, Wei; Pi, Xiong'e; Zhu, Liying; Yin, Yeshi; Yu, Guangli; Wang, Xin

    2016-06-01

    Alginate (Alg) has a long history as a food ingredient in East Asia. However, the human gut microbes responsible for the degradation of alginate and its derivatives have not been fully understood yet. Here, we report that alginate and the low molecular polymer derivatives of mannuronic acid oligosaccharides (MO) and guluronic acid oligosaccharides (GO) can be completely degraded and utilized at various rates by fecal microbiota obtained from six Chinese individuals. However, the derivative of propylene glycol alginate sodium sulfate (PSS) was not hydrolyzed. The bacteria having a pronounced ability to degrade Alg, MO and GO were isolated from human fecal samples and were identified as Bacteroides ovatus, Bacteroides xylanisolvens, and Bacteroides thetaiotaomicron. Alg, MO and GO can increase the production level of short chain fatty acids (SCFA), but GO generates the highest level of SCFA. Our data suggest that alginate and its derivatives could be degraded by specific bacteria in the human gut, providing the basis for the impacts of alginate and its derivates as special food additives on human health.

  7. Integration in a multilayer microfluidic chip of 8 parallel cell sorters with flow control by sol-gel transition of thermoreversible gelation polymer.

    Science.gov (United States)

    Sugino, Hirokazu; Arakawa, Takahiro; Nara, Yuki; Shirasaki, Yoshitaka; Ozaki, Kazuto; Shoji, Shuichi; Funatsu, Takashi

    2010-10-01

    Microfluidic systems have significant implications in the field of cell separation since they could provide platforms with inexpensive, disposable and sterile structures. Here, we present a novel strategy to integrate microfluidic sorters into a single chip for high throughput sorting. Our parallel sorter consists of a microfluidic chip with a three-dimensional channel network that utilizes flow switching by a heat-induced sol-gel transition of thermoreversible gelation polymer. The 8 parallel sheathed sample flows were realized by injecting sample and buffer solutions into only 2 inlets. The sheathed flows enabled disposal of unwanted sample waste without laser irradiation, and collection of wanted sample upon irradiation. As an application of the sorter, two kinds of fluorescent microspheres were separated with recovery ratio and purity of 70% or 90% at throughputs of about 100 or 20 particles per second, respectively. Next, Escherichia coli cells expressing green fluorescent protein were separated from those expressing DsRed with recovery ratio and purity of 90% at a throughput of about 20 cells per second. PMID:20689871

  8. Study the effect of ion-complex on the properties of composite gel polymer electrolyte based on Electrospun PVdF nanofibrous membrane

    International Nuclear Information System (INIS)

    In this paper, nanofibrous membranes based on poly(vinylidene fluoride) (PVdF) doped with ion-complex (SiO2-PAALi) were prepared by electrospinning technique and the corresponding composite gel-polymer electrolytes (CGPEs) were obtained after being activated in liquid electrolyte. The microstructure, physical and electrochemical performances of the nanofibrous membranes and the corresponding CGPEs were studied by various measurements such as Fourier Transform Infrared Spectroscopy(FTIR), Scanning Electron Microscope (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Stress-strain test, Linear Sweep Voltammetry (LSV), AC impedance measurement and Charge/discharge cycle test. As to the ion-complex doped nanofibrous membranes, PVdF can provide mechanical support with network structure composed of fully interconnection; while the ion-complexes are absorbed onto the surface of the PVdF nanofibers evenly instead of being aggregated. With the help of doped ion-complex, the prepared nanofibrous membranes present good liquid electrolyte absorbability, excellent mechanical performance, and high decomposition temperature. For the corresponding CGPEs, they possess high ionic conductivity, wide electrochemical window, and good charge/discharge cycle performance

  9. Improved photovoltaic performance of inverted polymer solar cells through a sol-gel processed Al-doped ZnO electron extraction layer.

    Science.gov (United States)

    Kim, Jun Young; Cho, Eunae; Kim, Jaehoon; Shin, Hyeonwoo; Roh, Jeongkyun; Thambidurai, Mariyappan; Kang, Chan-mo; Song, Hyung-Jun; Kim, SeongMin; Kim, Hyeok; Lee, Changhee

    2015-09-21

    We demonstrate that nanocrystalline Al-doped zinc oxide (n-AZO) thin film used as an electron-extraction layer can significantly enhance the performance of inverted polymer solar cells based on the bulk heterojunction of poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and [6,6]-phenyl C(71)-butyric acid methyl ester (PC(70)BM). A synergistic study with both simulation and experiment on n-AZO was carried out to offer a rational guidance for the efficiency improvement. As a result, An n-AZO film with an average grain size of 13 to 22 nm was prepared by a sol-gel spin-coating method, and a minimum resistivity of 2.1 × 10(-3) Ω·cm was obtained for an Al-doping concentration of 5.83 at.%. When an n-AZO film with a 5.83 at.% Al concentration was inserted between the ITO electrode and the active layer (PCDTBT:PC(70)BM), the power conversion efficiency increased from 3.7 to 5.6%. PMID:26406762

  10. Sol-gel derived multiwalled carbon nanotubes ceramic electrode modified with molecularly imprinted polymer for ultra trace sensing of dopamine in real samples

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Bhim Bali, E-mail: prof.bbpd@yahoo.com [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005 (India); Kumar, Deepak; Madhuri, Rashmi; Tiwari, Mahavir Prasad [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005 (India)

    2011-08-01

    Highlights: > MWCNTs-CE was prepared by silane acrylate which provides a nanometer thin MIP film. > The sensor was modified by iniferter and MIP using 'surface grafting-from approach'. > A comparative study was performed between differentially designed ceramic electrodes. > The sensor can detect dopamine in real samples with LODs (0.143-0.154 ng mL{sup -1}). - Abstract: A new class of composite electrodes made of sol-gel derived ceramic-multiwalled carbon nanotubes is used for the growth of a nanometer thin film adopting 'surface grafting-from approach'. For this the multiwalled carbon nanotubes-ceramic electrode surface is first modified with an iniferter (benzyl N,N-diethyldithiocarbamate) and then dopamine imprinted polymer, under UV irradiation, for differential pulse anodic stripping voltammetric sensing of dopamine in aqueous, blood serum, cerebrospinal fluid, and pharmaceutical samples (detection limit 0.143-0.154 ng mL{sup -1}, 3{sigma}), without any cross reactivity, interferences and false-positive contributions. Such composite electrodes offer higher stability, electron kinetics, and renewable porous surface of larger electroactive area (with insignificant capacitance) than carbon ceramic electrodes. Additional cyclic voltammetry (stripping mode) and chronocoulometry experiments were performed to explore electrodics and kinetics of electro-oxidation of dopamine.

  11. The potential of incorporation of binary salts and ionic liquid in P(VP-co-VAc) gel polymer electrolyte in electrochemical and photovoltaic performances

    Science.gov (United States)

    Ming, Ng Hon; Ramesh, S.; Ramesh, K.

    2016-06-01

    In this study, dye-sensitized solar cells (DSSCs) has been assembled with poly(1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) gel polymer electrolytes (GPEs) which have been incorporated with binary salt and an ionic liquid. The potential of this combination was studied and reported. The binary salt system GPEs was having ionic conductivity and power conversion efficiency (PCE) that could reach up to 1.90 × 10‑3 S cm‑1 and 5.53%, respectively. Interestingly, upon the addition of the ionic liquid, MPII into the binary salt system the ionic conductivity and PCE had risen steadily up to 4.09 × 10‑3 S cm‑1 and 5.94%, respectively. In order to know more about this phenomenon, the electrochemical impedance studies (EIS) of the GPE samples have been done and reported. Fourier transform infrared studies (FTIR) and thermogravimetric analysis (TGA) have also been studied to understand more on the structural and thermal properties of the GPEs. The Nyquist plot and Bodes plot studies have been done in order to understand the electrochemical properties of the GPE based DSSCs and Tafel polarization studies were done to determine the electrocatalytic activity of the GPE samples.

  12. Design and characterization of self-assembled fish sarcoplasmic protein-alginate nanocomplexes

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; Mattebjerg, Maria Ahlm; Wattjes, Jasper;

    2015-01-01

    Macrostructures based on natural polymers are subject to large attention, as the application range is wide within the food and pharmaceutical industries. In this study we present nanocomplexes (NCXs) made from electrostatic self-assembly between negatively charged alginate and positively charged ...

  13. Evaluation of dyes adsorption properties of TiO2-alginate biohybrid material

    Science.gov (United States)

    Barrón Zambrano, J. A.; Sánchez Morales, G.; Ávila Ortega, A.; Muñoz Rodríguez, D.; Carrera Figueiras, C.

    2013-06-01

    In this study a TiO2-alginate biohybrid material was obtained by the sol gel method and its adsorption properties were compared to those of its precursors using eosin B (anionic) as model dye. The results showed that the TiO2 and biohybrid have a greater affinity for eosine B than alginate. The maximum adsorption capacity for the eosin B was obtained at pH = 10. Kinetic studies showed that the biohybrid has greater rate and adsorption capacity than its precursors. Kinetic data were fitted to a pseudo-second order kinetic model. The experimental isotherms were fitted to the Langmuir model.

  14. 互穿聚合物网络凝胶调剖堵水剂的研究进展%Research progress of interpenetrating polymer network gel profile control and water plugging agent

    Institute of Scientific and Technical Information of China (English)

    李翠霞; 覃孝平

    2014-01-01

    Researehes both foreign and domestie on the interpenetrating polymer network gel profile eon-trol and water plugging agent are reviewed. The preparation methods,raw materials,formulas,properties and field applieation effeet of the interpenetrating polymer network gel profile eontrol and water plugging agent are diseussed. At the same time,the development trend of interpenetrating polymer network gel pro-file eontrol and water plugging agent is illustrated. The researeh results have eertain referenee value and guiding signifieanee to improve water flooding development effeet of high water eut oil field.%综述了互穿聚合物网络凝胶调剖堵水剂的国内外研究现状;阐述了互穿聚合物网络凝胶调剖堵水剂的制备方法、原料、配方、性能以及现场应用效果;同时指出了互穿聚合物网络凝胶调剖堵水剂的发展趋势。研究成果对改善高含水油田注水开发效果具有一定的参考价值和指导意义。

  15. Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media: Self-Assembly and Reversible Conversion of Vesicles and Gels%Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media: Self-Assembly and Reversible Conversion of Vesicles and Gels

    Institute of Scientific and Technical Information of China (English)

    杜平; 孔军; 王贵涛; 赵新; 李光玉; 蒋锡夔; 黎占亭

    2011-01-01

    In a preliminary letter (Tetrahedron Lett. 2010, 51, 188), we reported two new hydrazide-based quadruple hydrogen-bonding motifs, this is, two monopodal (la and lb) and five dipodal (2a, 2b and 3a--3c) aromatic hydrazide derivatives, and the formation of supramolecular polymers and vesicles from the dipodal motifs in hydrocarbons. In this paper, we present a full picture on the properties of these hydrogen-bonding motifs with an emphasis on their self-assembling behaviors in aqueous media. SEM, AFM, TEM and fluorescent micrographs indicate that all the dipodal compounds also form vesicles in polar methanol and water-methanol (up to 50% of water) mixtures. Control experiments show that lb does not form vesicles in same media. Addition of lb to the solution of the dipodal compounds inhibits the latter's capacity of forming vesicles. At high concentrations, 3b and 3c also gelate discrete solvents, including hydrocarbons, esters, methanol, and methanol-water mixture. Concentration-dependent SEM investigations reveal that the vesicles of 3b and 3c fuse to form gels and the gel of 3c can de-aggregate to form the vesicles reversibly.

  16. Composite Gel Polymer Electrolyte Based on Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) with Modified Aluminum-Doped Lithium Lanthanum Titanate (A-LLTO) for High-Performance Lithium Rechargeable Batteries.

    Science.gov (United States)

    Le, Hang T T; Ngo, Duc Tung; Kalubarme, Ramchandra S; Cao, Guozhong; Park, Choong-Nyeon; Park, Chan-Jin

    2016-08-17

    A composite gel polymer electrolyte (CGPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer that includes Al-doped Li0.33La0.56TiO3 (A-LLTO) particles covered with a modified SiO2 (m-SiO2) layer was fabricated through a simple solution-casting method followed by activation in a liquid electrolyte. The obtained CGPE possessed high ionic conductivity, a large electrochemical stability window, and interfacial stability-all superior to that of the pure gel polymer electrolyte (GPE). In addition, under a highly polarized condition, the CGPE effectively suppressed the growth of Li dendrites due to the improved hardness of the GPE by the addition of inorganic A-LLTO/m-SiO2 particles. Accordingly, the Li-ion polymer and Li-O2 cells employing the CGPE exhibited remarkably improved cyclability compared to cells without CGPE. In particular, the CGPE as a protection layer for the Li metal electrode in a Li-O2 cell was effective in blocking the contamination of the Li electrode by oxygen gas or impurities diffused from the cathode side while suppressing the Li dendrites. PMID:27463563

  17. PVA-H3 PO4凝胶聚合物电解质膜的制备及性能研究%Preparation of PVA-H3 PO4 Gel Polymer Electrolyte Membranes and Their Properties

    Institute of Scientific and Technical Information of China (English)

    张飞; 田琦峰; 李长春

    2016-01-01

    以磷酸作为交联引发剂和质子源,用戊二醛(GA)交联聚乙烯醇(PVA)制备 PVA-H3 PO4凝胶聚合物电解质膜。采用 X-射线衍射(XRD)、傅立叶变换红外光谱(FTIR)、热重分析(TGA)对制备的凝胶聚合物电解质膜进行了表征,并采用交流阻抗法研究了凝胶聚合物电解质膜的导电性能,分析了磷酸含量对凝胶聚合物电解质膜质子电导率的影响。结果表明,加入磷酸后,PVA结构由晶态向非晶态转变。随着 H3 PO4含量的增加,凝胶聚合物电解质膜的质子电导率先增大后减小;当PVA与 H3 PO4的质量比为1∶6时,在室温下其质子电导率可达0.093 S·cm-1,并且具有良好的电化学稳定性。%Using H3 PO4 as a cross-linking initiator and proton soure,PVA-H3 PO4 gel polymer electrolyte membranes were prepared by cross-linking glutaraldehyde(GA)with polyvinyl alcohol(PVA).The prepared gel polymer electrolyte membranes were characterized by X-ray diffraction(XRD),Fourier transform infrared spec-troscopy(FTIR)and thermogravimetric analysis(TGA).The conductivity of the gel polymer electrolyte mem-branes was investigated by an AC impedance method,and the effect of H3 PO4 content on the proton conductivi-ty of the gel polymer electrolyte membranes was also studied.Results showed that the structure of PVA trans-formed from crystalline state to amorphous state after addition of H3 PO4 .The proton conductivity of the gel polymer electrolyte membranes increased first and then decreased with the increase of H3 PO4 content.When the mass ratio of PVA and H3 PO4 was 1∶6,the proton conductivity reached 0.093 S·cm-1 at room temperature. Meanwhile,it had good electrochemical stability.

  18. Enhanced performance of a quasi-solid-state dye-sensitized solar cell with aluminum nitride in its gel polymer electrolyte

    KAUST Repository

    Huang, Kuan-Chieh

    2011-08-01

    The effects of incorporation of aluminum nitride (AlN) in the gel polymer electrolyte (GPE) of a quasi-solid-state dye-sensitized solar cell (DSSC) were studied in terms of performance of the cell. The electrolyte, consisting of lithium iodide (LiI), iodine (I2), and 4-tert-butylpyridine (TBP) in 3-methoxypropionitrile (MPN), was solidified with poly(vinyidene fluoride-co-hexafluoro propylene) (PVDF-HFP). The 0.05, 0.1, 0.3, and 0.5 wt% of AlN were added to the electrolyte for this study. XRD analysis showed a reduction of crystallinity in the polymer PVDF-HFP for all the additions of AlN. The DSSC fabricated with a GPE containing 0.1 wt% AlN showed a short-circuit current density (JSC) and power-conversion efficiency (η) of 12.92±0.54 mA/cm2 and 5.27±0.23%, respectively, at 100 mW/cm2 illumination, in contrast to the corresponding values of 11.52±0.21 mA/cm2 and 4.75±0.08% for a cell without AlN. The increases both in JSC and in η of the promoted DSSC are attributed to the higher apparent diffusion coefficient of I- in its electrolyte (3.52×10-6 cm2/s), compared to that in the electrolyte without AlN of a DSSC (2.97×10-6 cm 2/s). At-rest stability of the quasi-solid-state DSSC with 0.1 wt% of AlN was found to decrease hardly by 5% and 7% at room temperature and at 40 °C, respectively, after 1000 h duration. The DSSC with a liquid electrolyte showed a decrease of about 40% at room temperature, while it virtually lost its performance in about 150 h at 40 °C. Explanations are further substantiated by means of electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and by porosity measurements. © 2010 Elsevier B.V.

  19. Magnetic field-responsive release of transforming growth factor beta 1 from heparin-modified alginate ferrogels.

    Science.gov (United States)

    Kim, Hwi; Park, Honghyun; Lee, Jae Won; Lee, Kuen Yong

    2016-10-20

    Stimuli-responsive polymeric systems have been widely used for various drug delivery and tissue engineering applications. Magnetic stimulation can be also exploited to regulate the release of pharmaceutical drugs, growth factors, and cells from hydrogels in a controlled manner, on-demand. In the present study, alginate ferrogels containing iron oxide nanoparticles were fabricated via ionic cross-linking, and their various characteristics were investigated. The deformation of the ferrogels was dependent on the polymer concentration, calcium concentration, iron oxide concentration, and strength of magnetic field. To modulate the release of transforming growth factor beta 1 (TGF-β1) under magnetic stimulation, alginate was chemically modified with heparin, as TGF-β1 has a heparin-binding domain. Alginate was first modified with ethylenediamine, and heparin was then conjugated to the ethylenediamine-modified alginate via carbodiimide chemistry. Conjugation of heparin to alginate was confirmed by infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Sustained release of TGF-β1 from alginate-g-heparin ferrogels was achieved, and application of a magnetic field to the ferrogels regulated TGF-β1 release, resultantly enhancing chondrogenic differentiation of ATDC5 cells, which were used as a model chondrogenic cell line. Alginate-based ferrogels that release drugs in a controlled manner may therefore be useful in many biomedical applications. PMID:27474590

  20. Direct surface modification of high-voltage LiCoO2 cathodes by UV-cured nanothickness poly(ethylene glycol diacrylate) gel polymer electrolytes

    International Nuclear Information System (INIS)

    Highlights: • Direct surface modification of high-voltage LCO cathode by UV-cured PEGDA GPE. • Conformal PEGDA nanocoating layer is formed on LCO surface. • Preformed architecture of LCO cathode is not disrupted by PEGDA coating layer. • PEGDA-LCO cathode improves high-voltage cycling performance and thermal stability. • PEGDA nanocoating layer serves as a new ion-conductive protection film. -- Abstract: In the development of high-voltage lithium-ion batteries, unwanted interfacial side reactions between delithiated cathode materials and liquid electrolytes pose a formidable challenge that needs to be urgently resolved. In this study, as a simple and effective approach to improve cell performance and thermal stability of high-voltage cells, we demonstrate direct surface modification of a cathode by UV-cured nanothickness poly(ethylene glycol diacrylate) (PEGDA) gel polymer electrolyte (GPE). Herein, the UV-crosslinking of EGDA oligomers is conducted directly on as-formed cathode (LiCoO2 (LCO) is chosen as a model system), instead of application to LCO powders. This unusual coating process allows the successful formation of the conformal PEGDA nanocoating layer on the LCO surface without disrupting the preformed physical architecture of the LCO cathode (specifically, electronic networks and porous structure to be filled with liquid electrolyte). Owing to the structural novelty, the PEGDA-coated LCO cathode improves the cycling performance of high-voltage (=4.4 V) cells and suppresses the exothermic reaction between the delithiated LCO and liquid electrolyte, as compared to the pristine LCO cathode. These results underline that the conformal PEDGDA nanocoating layer proposed herein acts as a new ion-conductive protection film that effectively mitigates the undesired interfacial side reactions

  1. Carbopol 934-sodium alginate-gelatin mucoadhesive ondansetron tablets for buccal delivery: Effect of PH modifiers

    Directory of Open Access Journals (Sweden)

    Kotagale N

    2010-01-01

    Full Text Available The present work aims at developing mucoahesive tablets of ondansetron hydrochloride using bioadhesive polymers like carbopol-934, sodium alginate and gelatin. Tablets prepared by direct compression using different polymer with varying ratio were evaluated for hardness, friability, uniformity of weight, disintegration time, microenvironmental pH, bioadhesion and in vitro release. Hardness, friability disintegration time and drug release were found within pharmacopoeial limit. Microenvironmental pH decreased whereas bioadhesive strength, water uptake, and in vitro release increased with increase in carbopol-934. Increasing sodium alginate and gelatin increased the microenviromental pH and decreased bioadhesive strength, water uptake and in vitro release. With a view to investigate the modulation of drug release from formulation by addition of pH modifiers viz. citric acid and sodium bicarbonate, the tablets with carbopol-934 (2.0, sodium alginate (0.5 and gelatin (6.5 were used and the effect of pH modifiers on microenvironmental pH, bioadhesion, water uptake, in vitro permeation and in vitro release was studied. Microenvironmental pH, bioadhesive strength, water uptake, in vitro release and permeation decreased with increasing concentration of citric acid whereas microenvironmental pH, water uptake and release were enhanced and bioadhesive strength was lowered with increase in sodium bicarbonate. Present study demonstrates carbopol-934, sodium alginate, gelatin polymer system with added pH modifier can be successfully formulated for buccal delivery of ondansetron with desired release profile.

  2. Chitosan and alginate types of bio-membrane in fuel cell application: An overview

    Science.gov (United States)

    Shaari, N.; Kamarudin, S. K.

    2015-09-01

    The major problems of polymer electrolyte membrane fuel cell technology that need to be highlighted are fuel crossovers (e.g., methanol or hydrogen leaking across fuel cell membranes), CO poisoning, low durability, and high cost. Chitosan and alginate-based biopolymer membranes have recently been used to solve these problems with promising results. Current research in biopolymer membrane materials and systems has focused on the following: 1) the development of novel and efficient biopolymer materials; and 2) increasing the processing capacity of membrane operations. Consequently, chitosan and alginate-based biopolymers seek to enhance fuel cell performance by improving proton conductivity, membrane durability, and reducing fuel crossover and electro-osmotic drag. There are four groups of chitosan-based membranes (categorized according to their reaction and preparation): self-cross-linked and salt-complexed chitosans, chitosan-based polymer blends, chitosan/inorganic filler composites, and chitosan/polymer composites. There are only three alginate-based membranes that have been synthesized for fuel cell application. This work aims to review the state-of-the-art in the growth of chitosan and alginate-based biopolymer membranes for fuel cell applications.

  3. Cr3+聚合物凝胶成胶效果及其影响因素%Study on gelling effect of Cr3+polymer gel and its influence factors

    Institute of Scientific and Technical Information of China (English)

    卢祥国; 谢坤; 曹豹; 陈欣

    2015-01-01

    Although high-concentration polymer has strong viscoelasticity, there exist the compatibility problems between pol-ymer molecules aggregate size and reservoir rock pore size during its practical application. According to the geological charac-teristics and fluid properties of Daqing Oilfield reservoir, the viscoelasticity and oil displacement efficiency of the intramolec-ular cross-link polymer gel system were investigated after it was selected by orthogonal experiment through evaluating seepage characteristics, with core flow experiment and oil displacement experiment. It was found that intramolecular cross-link poly-mer gel system with smaller molecular aggregate, higher resistance coefficient and residual resistance coefficient can be ob-tained by regulating polymer concentration, water solution salinity and polymer/Cr3+. Once intramolecular cross-link reacted in polymer solution, on the one hand, transmission migration ability of polymer molecular clew is enhanced, and its rigidity is also improved. In this way, deformation ability of the polymer molecular clew is weakened when it flows through core pore, which can enhance the retention ability, increase the injection pressure and enlarge sweep volume effectively. On the other hand, the viscoelasticity and first normal stress difference of polymer gel system are improved, as well as the washing oil effi-ciency. The above two aspects insure jointly Cr3+ polymer gel has higher oil displacement efficiency.%高质量浓度聚合物具有较强的黏弹性,但应用中有时会出现聚合物分子聚集体尺寸与油藏岩石孔隙配伍性较差的问题。针对大庆油田储层地质特征和流体性质,通过岩心流动性实验和驱油实验,以渗流特性为评价指标,利用正交试验优选出分子内交联聚合物凝胶体系后,研究凝胶体系黏弹性和驱油效率。结果表明:调节聚合物质量浓度、配制水矿化度、w(聚/Cr3+)可获得分子聚集体尺寸较小

  4. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    International Nuclear Information System (INIS)

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation

  5. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    Energy Technology Data Exchange (ETDEWEB)

    Song, YoungShin; Lee, Chang-Soo [Chungnam National University, Daejeon (Korea, Republic of)

    2014-10-15

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation.

  6. Thromboresistant surface modification of expanded polytetrafluoroethylene vascular graft by impregnating covalently crosslinked gel of heparin and alginate%共价交联的肝素/海藻酸盐水凝胶表面修饰膨体聚四氟乙烯人工血管

    Institute of Scientific and Technical Information of China (English)

    马艳; 岳秀丽; 刘萌; 彭涛; 刘绍琴; 戴志飞

    2008-01-01

    BACKGROUND: The expanded polytetrafluoroethylene (ePTFE) vascular grafts hold promise for enhanced healing,extended suture retention, kink reduction and compression resistance. But thrombus formation still limits its use for revascularization of small-caliber vessels. It is the surface of ePTFE vascular graft that contacts with the blood. The current study focused on surface modification of ePTFE materials to improve its blood compatibility.OBJECTIVE: To characterize the heparin/alginate (H/A) gel modified ePTFE vascular graft and investigate the hemocompatibility and histocompatibility of the graft.DESIGN: Observation experiment.SETTING: Laboratory for Nanomedicine and Biosensor, Biomedicine Engineering Center, Harbin Institute of Technology.MATERIALS: The GORE-TEX ePTFE vascular grafts were 4 mm in internal diameter. Sodium alginate and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) were purchased from Sigma. Heparin sodium salt was obtained from Calbiochem. Nation and chitosan were purchased from Aldrich company. Human α-thrombin and AT Ⅲ were purchased from Haematologic Technologies, Inc. S-2238 was purchased from Chromogenix.METHODS: This study was performed at the Laboratory for Nanomedicine and Biosensor, Biomedicine Engineering Center, Harbin Institute of Technology between May 2006 and June 2007. The graft was first modified with Nation and then Chitosan/Nafion/Chitosan multilayer. Following the impregnation of heparin and alginate, covalent crosslinking was performed using ethylenediamine and EDC. Some characterization methods were employed: stastic water contact angle for the hydrophilicity; SEM for the surface morphology; ATR-FTIR for the surface chemical characteristics; APTT and PT,percent hemolysis and Chromogenic assay for the hemocompatibility of the ePTFE vascular graft after modification.MAIN OUTCOME MEASURES: ①Static water contact angles. ②Charactedzation of the surface morphology and platelet adhesion by SEM.

  7. CONFORMANCE IMPROVEMENT USING GELS

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Seright

    2004-09-30

    This report describes work performed during the third and final year of the project, ''Conformance Improvement Using Gels.'' Corefloods revealed throughput dependencies of permeability reduction by polymers and gels that were much more prolonged during oil flow than water flow. This behavior was explained using simple mobility ratio arguments. A model was developed that quantitatively fits the results and predicts ''clean up'' times for oil productivity when production wells are returned to service after application of a polymer or gel treatment. X-ray computed microtomography studies of gels in strongly water-wet Berea sandstone and strongly oil-wet porous polyethylene suggested that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than gel-ripping or gel-displacement mechanisms. In contrast, analysis of data from the University of Kansas suggests that the gel-ripping or displacement mechanisms are more important in more permeable, strongly water-wet sandpacks. These findings help to explain why aqueous gels can reduce permeability to water more than to oil under different conditions. Since cement is the most commonly used material for water shutoff, we considered when gels are preferred over cements. Our analysis and experimental results indicated that cement cannot be expected to completely fill (top to bottom) a vertical fracture of any width, except near the wellbore. For vertical fractures with apertures less than 4 mm, the cement slurry will simply not penetrate very far into the fracture. For vertical fractures with apertures greater than 4 mm, the slurry may penetrate a substantial distance into the bottom part of the fracture. However, except near the wellbore, the upper part of the fracture will remain open due to gravity segregation. We compared various approaches to plugging fractures using gels, including (1) varying polymer content, (2) varying placement (extrusion) rate

  8. Engineering alginate as bioink for bioprinting.

    Science.gov (United States)

    Jia, Jia; Richards, Dylan J; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P; Trusk, Thomas C; Yost, Michael J; Yao, Hai; Markwald, Roger R; Mei, Ying

    2014-10-01

    Recent advances in three-dimensional (3-D) printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been used extensively as bioinks for 3-D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations was prepared to develop a bioink platform that can be applied to a multitude of tissue engineering applications. The authors systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting the structure integrity of the lattice structures (except the highly degradable one) after 8days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  9. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation

    DEFF Research Database (Denmark)

    Stapper, A.P.; Narasimhan, G.; Oman, D.E.;

    2004-01-01

    Extracellular polymers can facilitate the non-specific attachment of bacteria to surfaces and hold together developing biofilms. This study was undertaken to qualitatively and quantitatively compare the architecture of biofilms produced by Pseudomonas aeruginosa strain PAO1 and its alginate......-overproducing (mucA22) and alginate-defective (algD) variants in order to discern the role of alginate in biofilm formation. These strains, PAO1, Alg(+) PAOmucA22 and Alg(-) PAOalgD, tagged with green fluorescent protein, were grown in a continuous flow cell system to characterize the developmental cycles...... of their biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (BIP) and Community Statistics (COMSTAT) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating...

  10. Release of tissue inhibitor of metalloproteinase-2 from alginate microcapsule encapsulating genetically engineered cells

    Directory of Open Access Journals (Sweden)

    Kim YS

    2013-11-01

    Full Text Available Yeon Seong Kim,1,* Young-Il Jeong,2,* Shu-Guang Jin,2 Jian Pei,2 Min Wen,2 In-Young Kim,1 Kyung-Sub Moon,1 Tae-Young Jung,1 Hyang-Hwa Ryu2, Shin Jung1–3 1Department of Neurosurgery, 2Brain Tumor Research Laboratory, 3Chonnam National University Research Institute of Medical Sciences, Chonnam National University Hwasun Hospital and Medical School, Jeollanam-do, Korea *These authors contributed equally to this work Background: In this study, 293T cells were genetically engineered to secrete tissue inhibitor of metalloproteinase-2 (TIMP2 and encapsulated into alginate microcapsules to continuously release TIMP2 protein. Methods: The anti-invasive potential of the microcapsules was studied in vitro using brain tumor cells. The TIMP2 gene was transfected to 293T cells, and genetically engineered 293TIMP2 cells were encapsulated into alginate microcapsules. Release of TIMP2 protein was detected with Western blot analysis and the anti-invasive potential against U87MG cells was tested using gelatin zymography and a Matrigel assay. Results: Cell viability within the alginate microcapsules was maintained at a cell density of 5 × 106. Because polycationic polymers are helpful for maintaining the mechanical strength of microcapsules with good cell viability, the alginate microcapsules were reinforced with chitosan (0.1% w/v. Expression of TIMP2 protein in cell lysates and secretion of TIMP2 into the conditioned medium was confirmed by Western blot analysis. Alginate microcapsules encapsulating 293TIMP2 cells released TIMP2 protein into the medium efficiently, where the TIMP2 protein participated in degradation of the matrix metalloproteinase-2 enzyme and inhibited invasion of U87MG cells. Conclusion: Alginate microcapsules encapsulating 293TIMP2 cells are promising candidates for anti-invasive treatment of glioma. Keywords: 293T cells, tissue inhibitor of metalloproteinase-2, alginate microcapsule, therapeutic protein

  11. Alginate cryogel based glucose biosensor

    Science.gov (United States)

    Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

    2016-02-01

    Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

  12. Radiation degradation of alginate and some results of biological effect of degraded alginate on plants

    Energy Technology Data Exchange (ETDEWEB)

    Hien, N.Q.; Hai, L.; Luan, L.Q.; Hanh, T.T. [Nuclear Research Institute, Dalat (Viet Nam); Nagasawa, Naotsugu; Yoshii, Fumio; Makuuchi, Keizo; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Radiation degradation yields (Gd) of alginate in aqueous solution with different concentration were determined by viscometry method. The relationship between Gd and the alginate concentration was found out as: Gd=33.5 x C{sup -0.68}, with C% (w/v) and dry alginate referred to C=100%. An empirical equation for preparing degraded alginate with the desired low viscometry average molecular weight (Mv) by radiation was proposed. Alginate extracted directly horn seaweed'Sagassum, degraded by radiation was used for field experiments and results of the biological effect on plants (tea, carrot, chrysanthemum) were presented. (author)

  13. Radiation degradation of alginate and some results of biological effect of degraded alginate on plants

    International Nuclear Information System (INIS)

    Radiation degradation yields (Gd) of alginate in aqueous solution with different concentration were determined by viscometry method. The relationship between Gd and the alginate concentration was found out as: Gd=33.5 x C-0.68, with C% (w/v) and dry alginate referred to C=100%. An empirical equation for preparing degraded alginate with the desired low viscometry average molecular weight (Mv) by radiation was proposed. Alginate extracted directly horn seaweed'Sagassum, degraded by radiation was used for field experiments and results of the biological effect on plants (tea, carrot, chrysanthemum) were presented. (author)

  14. Facile fabrication of organic-inorganic hybrid beads by aminated alginate enabled gelation and biomimetic mineralization.

    Science.gov (United States)

    Li, Jian; Wu, Hong; Liang, Yanpeng; Jiang, Zhongyi; Jiang, Yanjun; Zhang, Lei

    2013-01-01

    Inspired by biomineralization, design and preparation of biomimetic organic-inorganic composites have become a hot issue and a research frontier in many areas, including enzyme engineering. In this research, a unique and facile method for fabricating organic-inorganic hybrid beads is proposed. Modified alginate with a dual function of gelation and mineralization was synthesized for fabrication of hybrid carriers for enzyme immobilization. With the aid of EDC/NHS conjugation chemistry, the amine groups from diethylene triamine were grafted onto alginate in a controllable way. The resultant aminated alginate served manifold functions: forming a hydrogel via Ca(2+)-cross-linking, inducing the biomimetic silicification and manipulating the distribution of silica nanoparticles. Owing to the compact polymer network structure and the homogeneous silica nanoparticle dispersion, the as-prepared NH2-alginate/silica hybrid beads displayed superior swelling resistance and mechanical stability to pure alginate beads. The hybrid beads were subsequently utilized for encapsulation of yeast alcohol dehydrogenase (YADH). It was found that the thermal stability, pH tolerance and storage stability of the immobilized enzyme were all improved without significantly lowering the catalytic activity.

  15. Design and performance of a sericin-alginate interpenetrating network hydrogel for cell and drug delivery

    Science.gov (United States)

    Zhang, Yeshun; Liu, Jia; Huang, Lei; Wang, Zheng; Wang, Lin

    2015-07-01

    Although alginate hydrogels have been extensively studied for tissue engineering applications, their utilization is limited by poor mechanical strength, rapid drug release, and a lack of cell adhesive ability. Aiming to improve these properties, we employ the interpenetrating hydrogel design rationale. Using alginate and sericin (a natural protein with many unique properties and a major component of silkworm silk), we develop an interpenetrating polymer network (IPN) hydrogel comprising interwoven sericin and alginate double networks. By adjusting the sericin-to-alginate ratios, IPNs’ mechanical strength can be adjusted to meet stiffness requirements for various tissue repairs. The IPNs with high sericin content show increased stability during degradation, avoiding pure alginate’s early collapse. These IPNs have high swelling ratios, benefiting various applications such as drug delivery. The IPNs sustain controlled drug release with the adjustable rates. Furthermore, these IPNs are adhesive to cells, supporting cell proliferation, long-term survival and migration. Notably, the IPNs inherit sericin’s photoluminescent property, enabling bioimaging in vivo. Together, our study indicates that the sericin-alginate IPN hydrogels may serve as a versatile platform for delivering cells and drugs, and suggests that sericin may be a building block broadly applicable for generating IPN networks with other biomaterials for diverse tissue engineering applications.

  16. Molecular Weight and Branching Distribution Modeling in Radical Polymerization with Transfer to Polymer and Scission Under Gel Conditions and Allowing for Multiradicals

    NARCIS (Netherlands)

    N. Yaghini; P. Iedema

    2014-01-01

    A population balance model for the prediction of molecular weight distribution (MWD) in a continuous stirred tank reactor (CSTR) has been developed accounting for multiradicals and gel formation in the framework of Galerkin-FEM. In the absence of recombination, gel does not form, but accounting for

  17. Self-assembling polymer micelle/clay nanodisk/doxorubicin hybrid injectable gels for safe and efficient focal treatment of cancer.

    Science.gov (United States)

    Nagahama, Koji; Kawano, Daichi; Oyama, Naho; Takemoto, Ayaka; Kumano, Takayuki; Kawakami, Junji

    2015-03-01

    The purpose of this study was to fabricate a safe and effective doxorubicin (DOX)-delivery system for focal cancer chemotherapy. A novel biodegradable injectable gel was developed through self-assembly of poly(D,L-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA) copolymer micelles, clay nanodisks (CNDs), and DOX. We discovered that DOX loaded in the hybrid gels acts as an anticancer drug and as a building block to organize new gel networks. Accordingly, long-term sustained release of DOX from hybrid injectable gels without initial burst release was achieved. Moreover, it was revealed that the DOX incorporated into gel networks controls its own release profile. This hybrid injectable gel is a self-controlled drug release system, which is a novel concept in controlled drug release. Importantly, a single injection of PLGA-PEG-PLGA/CND/DOX hybrid gel provides long-term sustained antitumor activity in vivo against human xenograft tumors in mice, suggesting the potential of hybrid gels as a valuable local DOX-delivery platform for cancer focal therapy. PMID:25645815

  18. Electrospun Sodium Alginate/Polyethylene Oxide Fibers and Nanocoated Yarns

    Directory of Open Access Journals (Sweden)

    C. Hu

    2015-01-01

    Full Text Available Sodium alginate (NaAlg, as a natural biopolymer, was electrospun from aqueous solution via blending with a biofriendly synthetic polymer polyethylene oxide. The morphology and chemical properties of resultant alginate-based nanofibers were characterized by using scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, powder X-ray diffractometer (PXRD, and differential scanning calorimetry (DSC. At a wide voltage window (i.e., 12–24 kV, smooth and uniform nanofibers were obtained from the 5.0% concentration with the NaAlg/PEO ratio ranging from 1 : 1 to 1 : 3. The results from FTIR, PXRD, and DSC demonstrate that molecular interaction exists between these two polymers and, therefore, contributes to the alteration of crystallinity of electrospun fibers. In addition, NaAlg/PEO nanofiber-coated polylactic acid (PLA yarns with different twist levels were also fabricated in this work. The results show that the tensile strength of the nanocoated hybrid yarn and the tensile strength of uncoated yarn increase with the twist per centimeter (TPC up to 0.5 but decrease when TPC is further increased. The tensile properties of hybrid yarn are superior to those of the uncoated yarn.

  19. Spatial correlation of proton irradiation-induced activity and dose in polymer gel phantoms for PET/CT delivery verification studies

    International Nuclear Information System (INIS)

    Purpose: This work demonstrates a novel application of BANG3-Pro2 polymer gel dosimeter as a dosimetric phantom able to accurately capture both dose and induced activity. Methods: BANG3-Pro2 dosimeters were irradiated with a clinical proton beam using an unmodulated beam and a spread-out Bragg peak (SOBP) modulation, the latter with a Lucite compensator to introduce a range offset in one quadrant of the circular field. The dosimeters were imaged in a nearby positron emission tomography/computed tomography (PET/CT) unit starting within 5 min of beam-off. Induced positron emission (PE) activity along the central axis of the beam was compared to analytical calculations. Dose distributions were read out using an optical CT scanner and were validated against ion chamber measurements and the treatment plan. The offset between the distal fall-off of dose and activity (50% level) was determined over the entire irradiated field. Lateral profiles of PE were correlated to measured dose for the unmodulated beam delivery. Results: Measured profiles of PE activity along the central beam axis were found to be within 10% of the predictions of analytical calculations. The depth-dose profiles agreed with the reference values (ion chamber or treatment plan) within 3%. The offset between the depth profiles of dose and activity for the unmodulated beam was 8.4 ± 1.4 mm. For the compensator-based SOBP delivery, the distribution of offsets throughout the field was found to be bimodal, with the mean of 8.9 ± 2.8 mm for the thinner region of the compensator and 4.3 ± 2.5 mm for the thicker region. For the pristine beam delivery, lateral profiles of dose and activity were found to exhibit fair spatial correlation throughout the beam range, with the mean 2D gamma index of 0.42 and 91% of the evaluated pixels passing the test. Conclusions: This work presents the first demonstration of simultaneous and accurate experimental measurement of three-dimensional distributions of dose and induced

  20. Polymers in cell encapsulation from an enveloped cell perspective

    NARCIS (Netherlands)

    de Vos, Paul; Lazarjani, Hamideh Aghajani; Poncelet, Denis; Faas, Marijke M.

    2014-01-01

    In the past two decades, many polymers have been proposed for producing immunoprotective capsules. Examples include the natural polymers alginate, agarose, chitosan, cellulose, collagen, and xanthan and synthetic polymers poly(ethylene glycol), polyvinyl alcohol, polyurethane, poly(ether-sulfone), p

  1. Small SRS photon field profile dosimetry performed using a PinPoint air ion chamber, a diamond detector, a novel silicon-diode array (DOSI), and polymer gel dosimetry. Analysis and intercomparison.

    Science.gov (United States)

    Pappas, E; Maris, T G; Zacharopoulou, F; Papadakis, A; Manolopoulos, S; Green, S; Wojnecki, C

    2008-10-01

    Small photon fields are increasingly used in modern radiotherapy and especially in IMRT and SRS/SRT treatments. The uncertainties related to small field profile measurements can introduce significant systematic errors to the overall treatment process. These measurements are challenging mainly due to the absence of charged particle equilibrium conditions, detector size and composition effects, and positioning problems. In this work four different dosimetric methods have been used to measure the profiles of three small 6 MV circular fields having diameters of 7.5, 15.0, and 30.0 mm: a small sensitive volume air ion chamber, a diamond detector, a novel silicon-diode array (DOSI), and vinyl-pyrrolidone based polymer gel dosimeter. The results of this work support the validity of previous findings, suggesting that (a) air ion chambers are not suitable for small field dosimetry since they result in penumbra broadening and require significant corrections due to severe charged particle transport alterations; (b) diamond detectors provide high resolution and rather accurate small field profile measurements, as long as positioning problems can be addressed and the necessary dose rate corrections are correctly applied; and (c) the novel silicon-diode array (DOSI) used in this study seems to be adequate for small field profile measurements overcoming positioning problems. Polymer gel data were assumed as reference data to which the other measurement data were compared both qualitatively and quantitatively using the gamma-index concept. Polymer gels are both phantom and dosimeter, hence there are no beam perturbation effects. In addition, polymer gels are tissue equivalent and can provide high-spatial density and high-spatial resolution measurements without positioning problems, which makes them useful for small field dosimetry measurements. This work emphasizes the need to perform beam profile measurements of small fields (for acceptance, commissioning, treatment planning

  2. Preparation and characterization of hydroxyapatite/sodium alginate biocomposites for bone implant application

    Science.gov (United States)

    Kanasan, Nanthini; Adzila, Sharifah; Suid, Mohd Syafiq; Gurubaran, P.

    2016-07-01

    In biomedical fields, synthetic scaffolds are being improved by using the ceramics, polymers and composites materials to avoid the limitations of allograft. Ceramic-polymer composites are appearing to be the most successful bone graft substitute in human body. The natural bones itself are well-known as composite of collagen and hydroxyapatite. In this research, precipitation method was used to synthesis hydroxyapatite (HA)/sodium alginate (SA) in various parameters. This paper describes the hydroxyapatite/sodium alginate biocomposite which suitable for use in bone defects or regeneration of bone through the characterizations which include FTIR, FESEM, EDS and DTA. In FTIR, the characteristi peaks of PO4-3 and OH- groups which corresponding to hydroxyapatite are existed in the mixing powders. The needle-size particle of hydroxyapatite/ alginate (HA/SA) are observed in FESEM in the range of 15.8nm-38.2nm.EDS confirmed the existence of HA/SA composition in the mixing powders. There is an endothermic peak which corresponds to the dehydration and the loss of physically adsorbed water molecules of the hydroxyapatite (HA)/sodium alginate (SA) powder which are described in DTA.

  3. Effect of addition of inulin and fenugreek on the survival of microencapsulated Enterococcus durans 39C in alginate-psyllium polymeric blends in simulated digestive system and yogurt

    Directory of Open Access Journals (Sweden)

    Babak Haghshenas

    2015-07-01

    Full Text Available The use of biopolymers for probiotic microencapsulation has been investigated in this paper. The objectives are to enhance its survival rate, colonic release, and stability of these probiotic cultures in digestive condition during storage time. Nine types of biopolymers (alginate-psyllium blend with different concentration of prebiotic; (inulin or fenugreek were used as candidate for microencapsulation matrix. One strain of probiotic candidates, namely; Enterococcus durans 39C was used in this study. The microencapsulation of this strain with the respective polymer blend was performed by using a simple extrusion method. All blend of formulations have recorded high encapsulation efficiency at value >98%. The survival rate of viable probiotic cells under simulated digestive conditions was also high with value above 47% as compared to non-microencapsulated cells. These nine gel formulations also displayed the high survival rate of viable probiotic cells during storage time (28 d. Their release occurred after 2 h in colonic condition and sustained until 12th h of incubation period. An increase of prebiotic effect value added was observed in incorporated inulin and fenugreek formulations. In short, this study revealed that a new herbal-based psyllium and fenugreek polymers have suitable potential as a matrix for probiotic microencapsulation.

  4. Effect of free calcium concentration and ionic strength on alginate fouling in cross-flow membrane filtration

    NARCIS (Netherlands)

    Brink, van den P.; Zwijnenburg, A.; Smith, G.; Temmink, B.G.; Loosdrecht, van M.C.

    2009-01-01

    Extracellular polymeric substances (EPS) are generally negatively charged polymers. Membrane fouling in membrane bioreactors (MBRs) by EPS is therefore influenced by the water chemistry of the mixed liquor (calcium concentration, foulant concentration and ionic strength). We used alginate as a model

  5. Effect of Sodium Alginate Concentration on Membrane Strength and Permeating Property of Poly-l-arginine Group Microcapsule

    Institute of Scientific and Technical Information of China (English)

    Shi Bin WANG; Yuan Gang LIU; Lian Jin WENG; Xiao Jun MA

    2004-01-01

    A novel poly-l-arginine microcapsule was prepared due to its nutritional function and pharmacological efficacy. A high-voltage electrostatic droplet generator was used to make uniform microcapsules. The results show that the membrane strength and permeating property are both remarkably affected with the changes of sodium alginate concentration. With the sodium alginate concentration increasing, gel beads sizes increase from 233μm to 350μm, release ratio is also higher at the same time, but the membrane strength decreases.

  6. Determination of Microcystin-LR in waters in the subnanomolar range by sol–gel imprinted polymers on solid contact electrodes

    OpenAIRE

    Queirós, Raquel B.; Noronha, João P. C.; Marques, P.V.S.; Fernandes, João S.; M. Goreti F. Sales

    2012-01-01

    The present work reports new sensors for the direct determination of Microcystin-LR (MC-LR) in environmental waters. Both selective membrane and solid contact were optimized to ensure suitable analytical features in potentiometric transduction. The sensing layer consisted of Imprinted Sol–Gel (ISG) materials capable of establishing surface interactions with MC-LR. Non-Imprinted Sol–Gel (NISG) membranes were used as negative control. The effects of an ionic lipophilic additive, tim...

  7. PENGARUH UKURAN PARTIKEL DAN PROPORSI GULURONAT/MANURONAT DALAM ALGINAT TERHADAP SIFAT DAN SENSORIS PRODUK HASIL RESTRUKTURISASI DARI BUAH SIRSAK [The Influence of Particle size and Guluronic/Mannuronic Proportion of Alginate on Physical and Sensory Characteristics of Restructured Products from Soursop

    Directory of Open Access Journals (Sweden)

    Sri Raharjo

    2003-12-01

    Full Text Available The application of restructuring technology is intended to add value for local fruits. Fresh and ripe sour sop fruits are frequently of having defective appearance, irregular shape and size, or showing signs of insect infestation which make the whole fruit is less acceptable by consumers. Previous study has indicated that sour sop fruit can be restructured into a fresh fruit product with acceptable sensory characteristics using calcium alginate gel system. This particular study was intended to determine the effect of alginate powder particles size and its guluronic/mannuronic proportion on the physical and sensorial properties of restructured sour sop. The restructured fruit product was evaluated based on its gel strength, pH colour, and sensory attributes which include taste, aroma, mouth feel, appearance, and hardness. Sour sop restructured by internal setting with coarse alginate powder (36 mesh tend to have softer gel compared to the use of fine alginate powder (120 mesh. Different proportion of guluronic/mannuronic in the alginate used for the restructurization resulted in the same gel strength when calcium lactate powder was used. However, the use of encapsulated calcium lactate resulted in stronger gel with alginate containing higher proportion of mannuronic acid. The alginate particle size and proportion of guluronic/mannuronic content showed no significant difference in product colour and sensory attributes evaluated.

  8. Formation of magnetite nanoparticles in poly(acrylamide) gels

    Energy Technology Data Exchange (ETDEWEB)

    Starodubtsev, Sergey G [Physics Department, M V Lomonosov Moscow State University, Leninsky Gory, Moscow 119992 (Russian Federation); Saenko, Evheniy V [Physics Department, M V Lomonosov Moscow State University, Leninsky Gory, Moscow 119992 (Russian Federation); Dokukin, Maxim E [Physics Department, M V Lomonosov Moscow State University, Leninsky Gory, Moscow 119992 (Russian Federation); Aksenov, Viktor L [Physics Department, M V Lomonosov Moscow State University, Leninsky Gory, Moscow 119992 (Russian Federation); Klechkovskaya, Vera V [Institute of Crystallography, Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow 117333 (Russian Federation); Zanaveskina, Irina S [Institute of Crystallography, Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow 117333 (Russian Federation); Khokhlov, Alexei R [Physics Department, M V Lomonosov Moscow State University, Leninsky Gory, Moscow 119992 (Russian Federation)

    2005-03-16

    Magnetic gels with magnetite nanoparticles incorporated in a matrix of poly(acrylamide) gel were studied. Magnetite was synthesized through coprecipitation of Fe(II) and Fe(III) in the gel phase, in the solution of linear polymer and in aqueous solution without polymer in alkaline media. The effects of network structure and of the concentration of iron salts in the swollen networks on the composition, structure and properties of magnetic gels have been studied by electron diffraction, XRD, transmission electron microscopy and vibration sample magnetometry. The average size of magnetite nanoparticles, D, is of the order of 10 nm. It decreases with the increase of polymer concentration in the gel phase. In the dried gels the particles form spherical aggregates (diameter about 150 nm), whereas in the solution of linear polymer, in the aqueous solution of iron salts and in the gel with high content of polymer the aggregates have irregular shape.

  9. Radiation degradation of alginate and chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Naotsugu; Mitomo, Hiroshi [Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma (Japan); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Alginate and chitosan were irradiated in solid or aqueous solution condition with Co{sup 60} gamma rays in the dose range of 20 to 500 kGy. Degradation was observed both in solid and solution conditions. The degradation in solution was remarkably greater than that in solid. For example, the molecular weight of alginate in 4%(w/v) solution decreased from 2 x 10{sup 5} for 0 kGy to 6 x 10{sup 3} for 50 kGy irradiation while the equivalent degradation by solid irradiation required 500 kGy. The activated species from irradiated water must be responsible for the degradation in solution. The degradation was also accompanied with the color change of alginate: the color became deep brown for highly degraded alginate. UV spectra showed a distinct absorption peak at 265 nm for colored alginates, increasing with dose. The fact that discoloration of colored alginate was caused on exposure to ozone suggests a formation of double bond in pyranose-ring by scission of glycosidic bond. Degradation behavior of chitosan in irradiation was almost the same as that of alginate. (author)

  10. Composite alginate hydrogel microparticulate delivery system of zidovudine hydrochloride based on counter ion induced aggregation

    OpenAIRE

    Roy, Harekrishna; Rao, P. Venkateswar; Panda, Sanjay Kumar; Biswal, Asim Kumar; Parida, Kirti Ranjan; Dash, Jharana

    2014-01-01

    Aim: The present study deals with preparation of zidovudine loaded microparticle by counter ion induced aggregation method. During this study effect of polyacrylates and hypromellose polymers on release study were investigated. Materials and Methods: The ion induced aggregated alginate based microparticles were characterized for surface morphology, particle size analysis, drug entrapment study, in-vitro study, Fourier-transform infrared (FTIR) spectroscopy, and differential scanning calorimet...

  11. Theory of volume transition in polyelectrolyte gels with charge regularization

    OpenAIRE

    Hua, Jing; Mitra, Mithun K; Muthukumar, M.

    2012-01-01

    We present a theory for polyelectrolyte gels that allow the effective charge of the polymer backbone to self-regulate. Using a variational approach, we obtain an expression for the free energy of gels that accounts for the gel elasticity, free energy of mixing, counterion adsorption, local dielectric constant, electrostatic interaction among polymer segments, electrolyte ion correlations, and self-consistent charge regularization on the polymer strands. This free energy is then minimized to p...

  12. PREPARATION AND CHARACTERIZATION OF CINNARIZINE FLOATING OIL ENTRAPPED CALCIUM ALGINATE BEADS

    Directory of Open Access Journals (Sweden)

    Mowafaq M. Ghareeb et al.

    2012-02-01

    Full Text Available Gastroretentive delivery systems can be retained in the stomach and assist in improving absorption and consequently the bioavailability of drug that has a narrow absorption window in a particular region of gastrointestinal tract. A floatable multiparticulate system with potential for intragastric sustained delivery is one of the approaches to get the gastroretention. Cinnarizine(CNZ, an antihistaminic drug used in vertigo caused by meniere’s disease was taken as a model drug for floating beads prepared by non effervescent method. Floating CNZ olive oil-entrapped emulsion gel beads were prepared by the emulsion–gelation method. Different concentrations of sodium alginate (1%, 2%, and 3% w/v, oil (5%, 10%, and 15% v/v, and calcium chloride (0.02, 0.1, and 0.5M were used and their influence on beads uniformity, buoyancy, and in vitro drug release was studied. The results indicated that retardation of drug release was achieved by the oil hydrophobic diffusion barrier, especially in the presence of the compact network of alginate beads. The selected formula of calcium alginate beads using 3% w/v sodium alginate, 15% v/v oil and 0.1 M calcium chloride, showed a higher similarity factor (f2 =70.1 of CNZ release in comparison to release from standard gastroretentive sustained release floating cinnarizine tablet with good floating over duration of more than 12 hours.

  13. Selective removals of heavy metals (Pb(2+), Cu(2+), and Cd(2+)) from wastewater by gelation with alginate for effective metal recovery.

    Science.gov (United States)

    Wang, Fei; Lu, Xingwen; Li, Xiao-yan

    2016-05-01

    A novel method that uses the aqueous sodium alginate solution for direct gelation with metal ions is developed for effective removal and recovery of heavy metals from industrial wastewater. The experimental study was conducted on Pb(2+), Cu(2+), and Cd(2+) as the model heavy metals. The results show that gels can be formed rapidly between the metals and alginate in less than 10 min and the gelation rates fit well with the pseudo second-order kinetic model. The optimum dosing ratio of alginate to the metal ions was found to be between 2:1 and 3:1 for removing Pb(2+) and around 4:1 for removing Cu(2+) and Cd(2+) from wastewater, and the metal removal efficiency by gelation increased as the solution pH increased. Alginate exhibited a higher gelation affinity toward Pb(2+) than Cu(2+) and Cd(2+), which allowed a selective removal of Pb(2+) from the wastewater in the presence of Cu(2+) and Cd(2+) ions. Chemical analysis of the gels suggests that the gelation mainly occurred between the metal ions and the -COO(-) and -OH groups on alginate. By simple calcination of the metal-laden gels at 700 °C for 1 h, the heavy metals can be well recovered as valuable resources. The metals obtained after the thermal treatment are in the form of PbO, CuO, and CdO nanopowders with crystal sizes of around 150, 50, and 100 nm, respectively.

  14. Development of a morphogenetically active scaffold for three-dimensional growth of bone cells: biosilica-alginate hydrogel for SaOS-2 cell cultivation.

    Science.gov (United States)

    Müller, Werner E G; Schröder, Heinz C; Feng, Qingling; Schlossmacher, Ute; Link, Thorben; Wang, Xiaohong

    2015-11-01

    Polymeric silica is formed from ortho-silicate during a sol-gel formation process, while biosilica is the product of an enzymatically driven bio-polycondensation reaction. Both polymers have recently been described as a template that induces an increased expression of the genes encoding bone morphogenetic protein 2 (BMP-2) and osteoprotegerin in osteoblast-related SaOS-2 cells; simultaneously or subsequently the cells respond with enhanced hydroxyapatite formation. In order to assess whether the biocompatible polymeric silica/biosilica can serve as a morphogenetically active matrix suitable for three-dimensional (3D) cell growth, or even for 3D cell bioprinting, SaOS-2 cells were embedded into a Na-alginate-based hydrogel. Four different gelatinous hydrogel matrices were used for suspending SaOS-2 cells: (a) the hydrogel alone; (b) the hydrogel with 400 μM ortho-silicate; (c) the hydrogel supplemented with 400 μM ortho-silicate and recombinant silicatein to allow biosilica synthesis to occur; and (d) the hydrogel with ortho-silicate and BSA. The SaOS-2 cells showed an increased growth if silica/biosilica components were present in the hydrogel. Likewise intensified was the formation of hydroxyapatite nodules in the silica-containing hydrogels. After an incubation period of 2 weeks, cells present in silica-containing hydrogels showed a significantly higher expression of the genes encoding the cytokine BMP-2, the major fibrillar structural protein collagen 1 and likewise of carbonic anhydrase. It is concluded that silica, and to a larger extent biosilica, retains its morphogenetic/osteogenic potential after addition to Na-alginate-based hydrogels. This property might qualify silica hydrogels to be also used as a matrix for 3D cell printing.

  15. Luminescent spectroscopy and structural properties of Ce3+-doped low-temperature X1-Y2SiO5 material prepared by polymer-assisted sol-gel method

    Science.gov (United States)

    Hamroun, M. S. E.; Guerbous, L.; Bensafi, A.

    2016-04-01

    Cerium (Ce3+)-doped monoclinic X1-Y2SiO5 (YSO)-type oxyorthosilicates powders were prepared by monomer and polymer-assisted sol-gel method. The present work aims to study the influence of ethylene glycol (EG) monomer, polyethylene glycol (PEG) polymer and polyvinyl alcohol (PVA) polymer, as fuels and nucleating agents for the crystallization, on structural and luminescence properties of the Ce3+ (xCe = 0.01)-doped Y2SiO5. The X-ray diffraction technique, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and steady photoluminescence have been used to characterize the samples. It is found that the types of fuels affect the phase purity and luminescent characteristics of phosphors. All samples exhibit intense violet-blue asymmetric emission band in the range of 370-540 nm with a maximum intensity centered at around 420 nm assigned to the 5d → 4f (2F5/2, 2F7/2) interconfigurational transitions of Ce3+ ion in YSO nanomaterial. Finally, the vibronic coupling parameters are estimated and discussed.

  16. Physicochemical Characterization of Alginate Beads Containing Sugars and Biopolymers

    Directory of Open Access Journals (Sweden)

    Tatiana Aguirre Calvo

    2016-01-01

    Full Text Available Alginate hydrogels are suitable for the encapsulation of a great variety of biomolecules. Several alternatives to the conventional alginate formulation are being studied for a broad range of biotechnological applications; among them the addition of sugars and biopolymers arises as a good and economic strategy. Sugars (trehalose and β-cyclodextrin, a cationic biopolymer (chitosan, an anionic biopolymer (pectin, and neutral gums (Arabic, guar, espina corona, and vinal gums provided different characteristics to the beads. Here we discuss the influence of beads composition on several physicochemical properties, such as size and shape, analyzed through digital image analysis besides both water content and activity. The results showed that the addition of a second biopolymer, β-CD, or trehalose provoked more compact beads, but the fact that they were compact not necessarily implies a concomitant increase in their circularity. Espina corona beads showed the highest circularity value, being useful for applications which require a controlled and high circularity, assuring quality control. Beads with trehalose showed lower water content than the rest of the system, followed by those containing galactomannans (espina corona, vinal, and guar gums, revealing polymer structure effects. A complete characterization of the beads was performed by FT-IR, assigning the characteristics bands to each individual component.

  17. Avaliação do efeito da combinação de pectina, gelatina e alginato de sódio sobre as características de gel de fruta estruturada a partir de "mix" de polpa de cajá e mamão, por meio da metodologia de superfície de resposta Evaluation of the effects of pectin, gelatin and sodium alginate combination on the characteristics of a mixed structured fruit gel from papaya and yellow mobin, by response surface methodology

    Directory of Open Access Journals (Sweden)

    Ana Vania Carvalho

    2011-01-01

    Full Text Available Este trabalho teve por objetivo estabelecer procedimento tecnológico para produção de fruta estruturada a partir de "mix" de polpa de cajá e mamão, procurando unir as propriedades sensoriais de cada uma das frutas e potencializar as características funcionais do produto final. Avaliou-se o efeito da combinação de pectina, gelatina e alginato de sódio, via metodologia de superfície de resposta, nas características do gel de fruta. As polpas de mamão e cajá e os estruturados obtidos foram caracterizados com relação aos compostos funcionais, avaliando-se o teor de taninos e carotenóides totais, além das análises de composição centesimal, pH, acidez titulável, sólidos solúveis, açúcares, atividade de água, carboidratos e valor energético total. Os resultados obtidos através do planejamento experimental indicam que para o estruturado misto de cajá e mamão, somente o aumento da concentração de gelatina afeta a firmeza do produto final. Os estruturados de frutas desenvolvidos apresentaram boa aceitação sensorial para todos os atributos avaliados. Com relação à intenção de compra, 70% dos provadores responderam que provavelmente ou certamente, comprariam o estruturado misto de cajá e mamão se o encontrassem à venda.The objective of this work was to establish a technological procedure for producing a structured fruit product from yellow mobin and papaya purees, as an attempt to combine the sensory properties of both fruits and potentialize the functional properties of the final product. The effect of different combinations of pectin, gelatin and sodium alginate on the fruit gel properties was evaluated by response surface methodology. Papaya and yellow mobin purees and the structured products were characterized in terms of functional compounds (total tannin and carotenoid contents, as well as centesimal composition, pH, titratable acidity, soluble solids, sugars, water activity, carbohydrates and total energetic

  18. Programmed cell death in Laminaria japonica (Phaeophyta) tissues infected with alginic acid decomposing bacterium

    Institute of Scientific and Technical Information of China (English)

    WANG Gaoge; LIN Wei; ZHANG Lijing; YAN Xiaojun; DUAN Delin

    2004-01-01

    TdT-mediated dUTP-biotin nick end labeling (TUNEL) is a sensitive and valid method for detecting DNA cleavage in programmed cell death (PCD). Using this method, DNA cleavage was observed in Laminaria japonica sporophytic tissues, which were infected with alginic acid decomposing bacterium. It was found that DNA cleavage occurred 5 min after the infection, the fragments with 3′-OH groups of cleaved nuclear DNA increased with time of infection and spread from the infection site. Although no typical DNA ladder (200 bp/180 bp) was detected by routine agarose gel electrophoresis, the cleavage of nuclear DNA fragments of 97~48.5 kb could be detected by pulsed field gel electrophoresis (PFGE). By using CaspGLOWTM fluorescein active caspase-3 staining method, caspase-3 activity has been detected in response to the infection of alginic acid decomposing bacterium. Our results are similar to the observations in hypersensitive response (HR) of higher plant, suggesting that the rapid cell death of L. Japonica infected by alginic acid decomposing bacterium might be involved in PCD, and indicating that the occurrence of PCD is an active defense process against the pathogen's infection.

  19. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.;

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...... to evaluate the influence of the compatibility between gel and filler. Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong...... scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from...

  20. PCL/alginate composite scaffolds for hard tissue engineering: fabrication, characterization, and cellular activities.

    Science.gov (United States)

    Kim, Yong Bok; Kim, Geun Hyung

    2015-02-01

    Alginates have been used widely in biomedical applications because of good biocompatibility, low cost, and rapid gelation in the presence of calcium ions. However, poor mechanical properties and fabrication-ability for three-dimensional shapes have been obstacles in hard-tissue engineering applications. To overcome these shortcomings of alginates, we suggest a new composite system, consisting of a synthetic polymer, poly(ε-caprolactone), and various weight fractions (10-40 wt %) of alginate. The fabricated composite scaffolds displayed a multilayered 3D structure, consisting of microsized composite struts, and they provided a 100% offset for each layer. To show the feasibility of the scaffold for hard tissue regeneration, the composite scaffolds fabricated were assessed not only for physical properties, including surface roughness, tensile strength, and water absorption and wetting, but also in vitro osteoblastic cellular responses (cell-seeding efficiency, cell viability, fluorescence analyses, alkaline phosphatase (ALP) activity, and mineralization) by culturing with preosteoblasts (MC3T3-E1). Due to the alginate components in the composites, the scaffolds showed significantly enhanced wetting behavior, water-absorption (∼12-fold), and meaningful biological activities (∼2.1-fold for cell-seeding efficiency, ∼2.5-fold for cell-viability at 7 days, ∼3.4-fold for calcium deposition), compared with a pure PCL scaffold.

  1. Local structure of Ca(2+) induced hydrogels of alginate-oligoguluronate blends determined by small-angle-X-ray scattering.

    Science.gov (United States)

    Yuguchi, Yoshiaki; Hasegawa, Ami; Padoł, Anna Maria; Draget, Kurt Ingar; Stokke, Bjørn Torger

    2016-11-01

    Short oligoguluronates, oligoG's, are reported to affect the ionotropic gelation of alginates both with respect to altered gelation kinetics and elastic properties of the resulting gels. The local structure of Ca(2+) induced changes in oligoguluronates and blends of oligoguluronates and alginates was determined by small angle X-ray scattering (SAXS). Calcium was introduced in the aqueous polysaccharide solutions by in situ release of Ca(2+) from Ca-EGTA. The scattering profiles of the Ca(2+)-induced structures in the alginate-oligoG blends were accounted for by a two-component broken rod-like model, also with an additional term representing structural inhomogeneity by a Debye-Bueche term. Adding oligoG to the alginate yields an increase in the largest cross-sectional radius in the region of fractional Ca(2+) saturation of α-l-GulA units from 0.5 to 1. The time-lapse characterization during the Ca-induced changes in the alginate-oligoG blends shows that oligoG delays the emergence of the more extensive laterally aggregated junction zones.

  2. ESTUDIO DE PREFORMULACIÓN PARA EL DESARROLLO DE UN GEL A BASE DE POLÍMEROS CON CAPACIDAD MUCOADHESIVA PARA ENSAYOS DE ALELOPATÍA EN INVERTEBRADOS MARINOS. Preformulation study for the development of a polymer-based gel with mucoadhesive propierties for its use in allelopathy assays in marine invertebrates

    Directory of Open Access Journals (Sweden)

    Jenny Patricia Andrade

    Full Text Available La investigación se desarrolló con el fin de implementar una metodología que permitiera la realización de ensayos de interacciones alelopáticas entre corales y esponjas, minimizando la interacción física provocada por el uso de dispositivos que producen roce y efecto abrasivo sobre los pólipos del coral. Se llevó a cabo un estudio de preformulación utilizando polímeros con características mucoadhesivas sobre mucus que recubre los pólipos de coral, con el fin de obtener un gel, incorporando en las formulaciones un extracto de la esponja Cliona delitrix. Se caracterizaron propiedades como extensibilidad y adherencia, así como la capacidad bioadhesiva de las formulaciones propuestas, considerando su comportamiento reológico. Estas mostraron una buena estabilidad física frente a las condiciones del medio marino tanto in vitro como in situ. De igual manera, se diseñó un dispositivo que facilitó la aplicación del gel sobre la superficie de los corales por parte de los buzos en el arrecife coralino. Finalmente se estudió el comportamiento de liberación al medio acuoso simulado del gel con el extracto de la esponja objeto de estudioThis study was carried out with the purpose of implementing a methodology to assess allelopathic interactions assays between corals and reef sponges reducing the physical interaction caused by the use of devices that involve abrasion and harm over the coral polyps. Was carried out a preformulation study using polymers with mucoadhesive on the mucus that cover the coral polyps, with the purpose of develop a gel, incorporating an extract from Cliona Delitrix into the formulations. Obtained formulations were characterized by properties such as extensibility, adherence and mucoadhesive capacity. These formulations showed great physical stability under prevalent marine conditions both in vitro and in situ. In the same way was designed a device that let the smearing of the gel over the coral surfaces carried

  3. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    Science.gov (United States)

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-01-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %.

  4. Radiation Synthesis of Superabsorbent Polymers Based on Natural Polymers

    International Nuclear Information System (INIS)

    The objectives of proposed research contract were first synthesize superabsorbent polymers based on natural polymers to be used as disposable diapers and soil conditioning materials in agriculture, horticulture and other super adsorbent using industries. We have planned to use the natural polymers; locust beam gum, tara gum, guar gum and sodium alginate on the preparation of natural superabsorbent polymers(SAP). The aqueous solution of natural polymers and their blends with trace amount of monomer and cross-linking agents will be irradiated in paste like conditions by gamma rays for the preparation of cross-linked superabsorbent systems. The water absorption and deswellling capacity of prepared super adsorbents and retention capacity, absorbency under load, suction power, swelling pressure and pet-rewet properties will be determined. Use of these materials instead of synthetic super absorbents will be examined by comparing the performance of finished products. The experimental studies achieved in the second year of project mainly on the effect of radiation on the chemistry of sodium alginate polymers in different irradiation conditions and structure-property relationship particularly with respect to radiation induced changes on the molecular weight of natural polymers and preliminary studies on the synthesis of natural-synthetic hydride super adsorbent polymers were given in details

  5. PLGA/alginate composite microspheres for hydrophilic protein delivery

    International Nuclear Information System (INIS)

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate. - Highlights: • A double emulsion technique is used to prepare protein-loaded PLGA or PLGA/alginate microspheres. • PLGA, alginate and protein are distributed evenly within microsphere structure. • Addition of alginate improves loading efficiency and slows degradation and protein release. • PLGA/alginate microspheres have favorable biocompatibility

  6. PLGA/alginate composite microspheres for hydrophilic protein delivery

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Peng [Department of Anatomy and Cell Biology, University of Saskatchewan, S7N5E5 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada); Chen, X.B. [Department of Mechanical Engineering, University of Saskatchewan, S7N5A9 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada); Schreyer, David J., E-mail: david.schreyer@usask.ca [Department of Anatomy and Cell Biology, University of Saskatchewan, S7N5E5 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada)

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate. - Highlights: • A double emulsion technique is used to prepare protein-loaded PLGA or PLGA/alginate microspheres. • PLGA, alginate and protein are distributed evenly within microsphere structure. • Addition of alginate improves loading efficiency and slows degradation and protein release. • PLGA/alginate microspheres have favorable biocompatibility.

  7. Will the use of double barrier result in sustained release of vancomycin? Optimization of parameters for preparation of a new antibacterial alginate-based modern dressing.

    Science.gov (United States)

    Kurczewska, Joanna; Sawicka, Paulina; Ratajczak, Magdalena; Gajęcka, Marzena; Schroeder, Grzegorz

    2015-12-30

    The aim of this research was to prepare and characterize an alginate-based wound dressing containing vancomycin immobilized at the silica surface. The silica samples functionalized with amine, diol and carboxylic acid groups were loaded with 7.8, 5.7 and 7.1wt.% of the antibiotic respectively. The immobilized drug was encapsulated in alginate or gelatin/alginate gels and the average concentration of vancomycin was about 10mg per g of the dried gel. The effect of functional organic groups at the silica surface on the release rate of the drug was investigated. Only the drug immobilized at Si-amine in alginate matrix was found to demonstrate slower release from the proposed wound dressing. The in vitro release profiles for other silica carriers did not show significant differences in relation to the free loaded drug. The presence of gelatin had a favourable impact on the slowing down of the drug release from the dressing with a double barrier. All the gels studied with vancomycin immobilized at the silica surface demonstrated antimicrobial activity against various bacteria. A reduction of the drug dose to a half had no effect on changing microbiological activity of gels.

  8. Pulsed-low intensity ultrasound enhances extracellular matrix production by fibroblasts encapsulated in alginate

    Directory of Open Access Journals (Sweden)

    Siti PM Bohari

    2012-07-01

    Full Text Available In this study, the effect of pulsed-low intensity ultrasound on cell proliferation, collagen production and glycosaminoglycan deposition by 3T3 fibroblasts encapsulated in alginate was evaluated. Hoechst 33258 assay for cell number, hydroxyproline assay for collagen content and dimethylamine blue assay for glycosaminoglycan content were performed on samples from cell cultures treated with pulsed-low intensity ultrasound and a control group. Pulsed-low intensity ultrasound shows no effect on cell proliferation, while collagen and glycosaminoglycan contents were consistently higher in the samples treated with pulsed-low intensity ultrasound, showing a statistically significant difference (p < 0.05 on day 10. Alcian blue staining showed that glycosaminoglycans were deposited around the cells in both groups. These results suggest that pulsed-low intensity ultrasound shows no effect on cell proliferation but has potential for inducing collagen and glycosaminoglycan production in cells cultured in alginate gels.

  9. Pulsed-low intensity ultrasound enhances extracellular matrix production by fibroblasts encapsulated in alginate

    Directory of Open Access Journals (Sweden)

    Siti PM Bohari

    2012-12-01

    Full Text Available In this study, the effect of pulsed-low intensity ultrasound on cell proliferation, collagen production and glycosaminoglycan deposition by 3T3 fibroblasts encapsulated in alginate was evaluated. Hoechst 33258 assay for cell number, hydroxyproline assay for collagen content and dimethylamine blue assay for glycosaminoglycan content were performed on samples from cell cultures treated with pulsed-low intensity ultrasound and a control group. Pulsed-low intensity ultrasound shows no effect on cell proliferation, while collagen and glycosaminoglycan contents were consistently higher in the samples treated with pulsed-low intensity ultrasound, showing a statistically significant difference (p < 0.05 on day 10. Alcian blue staining showed that glycosaminoglycans were deposited around the cells in both groups. These results suggest that pulsed-low intensity ultrasound shows no effect on cell proliferation but has potential for inducing collagen and glycosaminoglycan production in cells cultured in alginate gels.

  10. Novel tamarind seed polysaccharide-alginate mucoadhesive microspheres for oral gliclazide delivery: in vitro-in vivo evaluation.

    Science.gov (United States)

    Pal, Dilipkumar; Nayak, Amit Kumar

    2012-04-01

    Novel tamarind seed polysaccharide (TSP)-alginate mucoadhesive microspheres were prepared using TSP and alginate as blend in different ratios with different calcium chloride (CaCl(2)) concentration as a cross linker by ionotropic gelation. The prepared microspheres were of spherical shape having rough surfaces, and average particle sizes within the range of 752.12 ± 6.42 to 948.49 ± 20.92 µm. The drug entrapment efficiency of these microspheres were within the range between 58.12 ± 2.42 to 82.78 ± 3.43% w/w. Fourier transform infrared (FTIR) studies indicated that there were no reactions between gliclazide, and polymers (TSP, and sodium alginate) used. Different formulations of gliclazide loaded TSP-alginate microspheres showed prolonged in vitro release profiles of gliclazide over 12 hours in both stomach pH (pH 1.2), and intestinal pH (pH 7.4). It was found that the gliclazide release in gastric pH was comparatively slow and sustained than intestinal pH. These TSP-alginate microspheres also exhibited good mucoadhesivity. The in vivo studies on alloxan-induced diabetic rats (Animal Ethical Committee registration number: IFTM/837ac/0160) demonstrated the significant hypoglycemic effect of selected formulation of TSP-alginate mucoadhesive microspheres containing gliclazide on oral administration. This developed gliclazide loaded new TSP-alginate mucoadhesive microspheres may be very much useful for prolonged systemic absorption of gliclazide for proper maintaining blood glucose level and advanced patient compliance.

  11. Characterization of algG encoding C5-epimerase in the alginate biosynthetic gene cluster of Pseudomonas fluorescens.

    Science.gov (United States)

    Morea, A; Mathee, K; Franklin, M J; Giacomini, A; O'Regan, M; Ohman, D E

    2001-10-31

    The organization of the alginate gene cluster in Pseudomonas fluorescens was characterized. A bank of genomic DNA from P. fluorescens was mobilized to a strain of Pseudomonas aeruginosa with a transposon insertion (algJ::Tn501) in the alginate biosynthetic operon that rendered it non-mucoid. Phenotypic complementation in this heterologous host was observed, and a complementing clone containing 32 kb of P. fluorescens DNA was obtained. Southern hybridization studies showed that genes involved in alginate biosynthesis (e.g. algD, algG, and algA) were approximately in the same order and position as in P. aeruginosa. When the clone was mobilized to a P. aeruginosa algG mutant that produced alginate as polymannuronate due to its C5-epimerase defect, complementation was observed and the alginate from the recombinant strain contained L-guluronate as determined by proton nuclear magnetic resonance spectroscopy. A sequence analysis of the P. fluorescens DNA containing algG revealed sequences similar to P. aeruginosa algG that were also flanked by algE- and algX-like sequences. The predicted AlgG amino acid sequence of P. fluorescens was 67% identical (80% similar) to P. aeruginosa AlgG and 60% identical (76% similar) to Azotobacter vinelandii AlgG. As in P. aeruginosa, AlgG from P. fluorescens appeared to have a signal sequence that would localize it to the periplasm where AlgG presumably acts as a C5-epimerase at the polymer level. Non-polar algG knockout mutants of P. fluorescens were defective in alginate production, suggesting a potential role for this protein in polymer formation.

  12. Development of water-repellent organic–inorganic hybrid sol–gel coatings on aluminum using short chain perfluoro polymer emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Wankhede, Ruchi Grover, E-mail: 123.ruchi@gmail.com [IITB-Monash Research Academy, Mumbai 400076 (India); Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Morey, Shantaram [Dow Chemicals (India); Khanna, A.S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Birbilis, N. [Department of Materials Engineering, Monash University, Victoria 3800 (Australia)

    2013-10-15

    The development of an organic–inorganic sol–gel coating system (thickness ∼ 2 μm) on aluminum is reported. The coating uses glycidoxytrimethoxysilane (GPTMS) and methyltrimethoxysilane (MTMS) as silane precursors, crosslinked with hexamethylmethoxymelamine (HMMM) and followed by hydrophobic modification using a water base short chain per-fluoro emulsion (FE). Such coating resulted in enhanced hydrophobicity with a contact angle of about 120° and sliding angle of 25° for a 20 μL water droplet. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements showed reduced corrosion upon coated substrates than the bare; correlated with both a higher degree of water repellency and formation of low permeable crosslinked sol–gel network. The structure of the coatings deposited was analyzed using Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy, revealing replacement of hydrophillic surface hydroxyls groups with low energy per-fluoro groups.

  13. Cyclization Phenomena in the Sol-Gel Polymerization of a,w-Bis(triethoxysilyl)alkanes and Incorporation of the Cyclic Structures into Network Silsesquioxane Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Alam, T.M.; Carpenter, J.P.; Dorhout, P.K.; Greaves, J.; Loy, D.A.; Shaltout, R.; Shea, K.J.; Small, J.H.

    1999-01-04

    Intramolecular cyclizations during acid-catalyzed, sol-gel polymerizations of ct,co- bis(tietioxysilyl)aWmes substintidly lengtien gelties formonomers witietiylene- (l), propylene- (2), and butylene-(3)-bridging groups. These cyclizations reactions were found, using mass spectrometry and %i NMR spectroscopy, to lead preferentially to monomeric and dimeric products based on six and seven membered disilsesquioxane rings. 1,2- Bis(triethoxysilyl)ethane (1) reacts under acidic conditions to give a bicyclic drier (5) that is composed of two annelated seven membered rings. Under the same conditions, 1,3- bis(triethoxysilyl)propane (2), 1,4-bis(triethoxysilyl)butane (3), and z-1,4- bis(triethoxysilyl)but-2-ene (10) undergo an intramolecular condensation reaction to give the six membemd and seven membered cyclic disilsesquioxanes 6, 7, and 11. Subsequently, these cyclic monomers slowly react to form the tricyclic dirners 8,9 and 12. With NaOH as polymerization catalyst these cyclic silsesquioxanes readily ~aeted to afford gels that were shown by CP MAS z%i NMR and infr=d spectroscopes to retain some cyclic structures. Comparison of the porosity and microstructwe of xerogels prepared from the cyclic monomers 6 and 7 with gels prepared directly from their acyclic precursors 2 and 3, indicate that the final pore structure of the xerogels is markedly dependent on the nature of the precursor. In addition, despite the fact that the monomeric cyclic disilsesquioxane species can not be isolated from 1-3 under basic conditions due to their rapid rate of gelation, spectroscopic techniques also detected the presence of the cyclic structures in the resulting polymeric gels.

  14. Preparation and properties of PEO/LiClO4/KH560-SiO2 composite polymer electrolyte by sol-gel composite-in-situ method

    Institute of Scientific and Technical Information of China (English)

    PAN Chun-yue; GAO Jin-huan; ZHANG Qian; FENG Qing; CHAO meng

    2008-01-01

    Composite polymer electrolytes based on polyethylene oxide (PEO) were prepared by using LiClO4 as doping salt and silane-modified SiO2 as filler. SiO2 was formed in-situ in (PEO)8LiClO4 matrix by the hydrolysis and condensation reaction of Si(OC4H9)4. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry, scanning electron microscopy, atom force microscopy and alternating current impedance spectroscopy, respectively. Compared with the crystallinity of the unmodified SiO2 as inert filler, that of composite polymer electrolytes is decreased. The results show that silane-modified SiO2 particles are uniformly dispersed in (PEO)8LiClO4 composite polymer electrolyte film and the addition of silane-modified SiO2 increases the ionic conductivity of the (PEO)8LiClO4 more noticeably. When the mass fraction of SiO2 is about 10%, the conductivity of (PEO)8LiClO4-modified SiO2 attains a maximum value of 4.8×10-5S·cm-1.

  15. Polymeric microcapsules poduction from sodium alginic acid for cell therapy

    Directory of Open Access Journals (Sweden)

    Ana Carolina Vale Campos Lisboa

    2007-12-01

    Full Text Available Development of polymeric materials has been increasingly emphasized in Biomedicine. Here, we evaluate the use of microcapsules made of Biodritin®, a biocompatible polymer compound which contains sodium alginic acid, a natural polymer extracted from algae, and Cis-Chondroitin sulfate, a glycosaminoglycan from the extracellular matrix. Gelation of this polymer into microcapsules is achieved by dropping the compound into BaCl2 or CaCl2 gelling solutions. A functional microcapsule is dependent on its permeability, mechanical stability, immunoisolation capacity and biocompatibility. The mechanical stability of Biodritin-barium and Biodritin-calcium microcapsules was investigated after rotational stress upon in vitro culture and in vivo implantation. Viability studies of encapsulated cells were also performed to assess other functional parameters of the microcapsules. When subject to rotational stress, Biodritin-barium microcapsules exhibited breaks, whereas the Biodritin-calcium microcapsules did not. Both kinds of Biodritin® microcapsules proved to be mechanically resistant in in vitro and in vivo studies. However, the Biodritin-calcium material was found to be more elastic while the Biodritin-barium microcapsules displayed a more plastic behavior. These properties seem to be determinant for viability of the encapsulated cell’s, since the Biodritin-calcium microcapsules presented more viable cells than the Biodritin-barium microcapsules.

  16. Evaluation of Radiation Processed Polymers as Materials for Agricultural Purposes. Chapter 8

    International Nuclear Information System (INIS)

    The use of ionizing radiation in the development of natural and synthetic polymers for agricultural purposes has proven to be successful. Polysaccharides such as chitosan and sodium alginate are easily degraded through ionizing radiation which is considered to be a safe, clean, and an environment-friendly method. As a result, different kinds of biologically active fragments possessing growth promotion properties for plant performance and antimicrobial activities against pathogenic microorganisms for food preservation were obtained. Several factors such as preparation conditions, quality of the new materials, safety of the materials especially where the environment is concerned, and economic feasibility and production cost have been studied in its aim to commercialize the products. The required dose for degradation of soluble polysaccharide is relatively low when compared with that of solid polysaccharides. From the economic point of view, the choice to degrade polysaccharide with the use of viscous polysaccharide solutions containing 0.5–1 wt% oxidizing agent such as H2O2 is necessary to decrease the dose required for degradation in the range of 20–30 kGy. Average molecular weights (MW) as well as molecular weights distributions were accurately determined by using different techniques like gel permeation chromatography (GPC) and viscometer. Large scale field studies of degraded polysaccharide materials as a growth promoter or an elicitor for different crops like wheat, faba bean, zea maze, and other vegetables and fruits (e.g. tomato, hot pepper, and banana crops) have been carried out. It was found that the treatment with low MW alginate of plants such as wheat increased its productivity by 25–30%, improved the quality of the crop, and enhanced the capability of wheat seeds to be used for long-term cultivation. The use of irradiated polysaccharides in stimulating defense reactions against some diseases in some plants was studied. Sodium alginates had a high

  17. Monomer consumption in MAGIC-type polymer gels in the Bragg-peak of proton beams observed by volume selective 1H MR-spectroscopy (MRS): proof of principle for high resolution MRS-methodology with a sensitive rf-detector

    International Nuclear Information System (INIS)

    Mono-energetic proton and heavy ion beams for tumour therapy feature high dose gradients laterally and at its penetration depth, characterized by the Bragg-peak. The 3-dimensional dosimetry of such Hadron particle beams poses high demands on the spatial resolution of the imaging methodology and linearity of the polymer gel dose response in a wide dose range and at high linear energy transfer (LET). In almost all polymer gels the Bragg-peak dose response is therefore quenched. Volume selective MR-spectroscopy is in principle capable of delivering information on the polymerization process. We here present the MR-methodology to obtain MR-spectroscopic (MRS) data on the monomer consumption at the very small voxel volumes necessary for resolving e.g. the Bragg-peak area. Using additional hardware components, i.e. a strong gradient system and a very sensitive rf-detector at a high field human 7T scanner, MR-microimaging and MRS with 600 μm depth resolution can be implemented at very short measurement time. The vinyl groups of methacrylic acid in a MAGIC-type polymer gel can be resolved by volume selective MRS. The complete monomer consumption in the Bragg-peak due to polymerization is demonstrated selectively in the Bragg-peak indicating one main reason for Bragg-peak quenching in the investigated polymer gel.

  18. Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System.

    Science.gov (United States)

    Venkatesan, Shanmuganathan; Liu, I-Ping; Chen, Li-Tung; Hou, Yi-Chen; Li, Chiao-Wei; Lee, Yuh-Lang

    2016-09-21

    Polymer gel electrolytes (PGEs) of cobalt redox system are prepared for dye sensitized solar cell (DSSC) applications. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is used as a gelator of an acetonitrile (ACN) liquid electrolyte containing tris(2,2'-bipyridine)cobalt(II/III) redox couple. Titanium dioxide (TiO2) and titanium carbide (TiC) nanoparticles are utilized as nanofillers (NFs) of this PGE, and the effects of the two NFs on the conductivity of the PGEs, charge-transfer resistances at the electrode/PGE interface, and the performance of the gel-state DSSCs are studied and compared. The results show that the presence of TiC NFs significantly increases the conductivity of the PGE and decreases the charge-transfer resistance at the Pt counter-electrode (CE)/PGE interface. Therefore, the gel-state DSSC utilizing TiC NFs can achieve a conversion efficiency (6.29%) comparable to its liquid counterpart (6.30%), and, furthermore, the cell efficiency can retain 94% of its initial value after a 1000 h stability test at 50 °C. On the contrary, introduction of TiO2 NFs in the PGE causes a decrease of cell performances. It shows that the presence of TiO2 NFs increases the charge-transfer resistance at the Pt CE/PGE interface, induces the charge recombination at the photoanode/PGE interface, and, furthermore, causes a dye desorption in a long-term-stability test. These results are different from those reported for the iodide redox system and are ascribed to a specific attractive interaction between TiO2 and cobalt redox ions.

  19. Controlling Radiation Degradation of Natural Polymers for Industrial and Agricultural application

    International Nuclear Information System (INIS)

    Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. The addition of some additives such as potassium per-sulfate (KPS), ammonium per-sulfate (APS), or H2O2 to natural polymers such as chitosan and Na-alginate during irradiation process accelerates their degradation. The highest degradation rate of polysaccharides obtained when APS was used. The end product of irradiated chitosan, and Na-alginate may be used as food additive or benefited in agricultural purposes. The prepared crosslinked copolymers possessed high and fast swelling properties in simulated urine media and the swelling ratios of CMC-Na /PAAm gels in urine are acceptable for diaper application. (author)

  20. TEMPO-oxidized nanocellulose participating as crosslinking aid for alginate-based sponges.

    Science.gov (United States)

    Lin, Ning; Bruzzese, Cécile; Dufresne, Alain

    2012-09-26

    Crosslinked polysaccharide sponges have been prepared by freeze-drying of amorphous alginate-oxidized nanocellulose in the presence of a Ca(2+) ionic crosslinking agent. The new carboxyl groups on the surface of nanocellulose induced by the chemical oxidization provided the possibility of participating in the construction of an alginate-based sponge's structure and played a fundamental role in the structural and mechanical stability of ensuing sponges. Furthermore, enhanced mechanical strength induced by oxidized cellulose nanocrystals and the formation of a semi-interpenetrating polymer network from oxidized microfibrillated cellulose were reported. Together with the facile and ionic crosslinking process, the ultrahigh porosity, promising water absorption and retention, as well as the improved compression strength of the crosslinked sponges should significantly extend the use of this soft material in diverse practical applications. PMID:22950801

  1. Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction: I. Determination of methadone in human plasma utilizing liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    El-Beqqali, Aziza; Abdel-Rehim, Mohamed

    2016-09-14

    In the present work molecularly imprinted sol-gel tablet (MIP-Tablet) was prepared. The MIP-sol-gel was prepared as a thin layer on polyethylene material in a tablet form. Methadone-d9 was selected as the template and 3-(propylmethacrylate)-trimethoxysilane was used as precursor. MIP-Tablet was applied for micro-solid phase extraction (μ-SPE). The MIP-Tablet was used for the determination of methadone in human plasma samples utilizing liquid chromatography-tandem mass spectrometry; and each tablet could be used twenty times. The extraction time was 10 min while desorption time was 6 min. Factors affecting the extraction efficiency such as desorption solvents, sample pH, salt addition, extraction time, desorption time and adsorption capacity were investigated. The calibration curves were obtained within the range of 5-5000 ng/mL using methadone in human plasma samples. The coefficients of determination (r(2)) values were ≥0.999 for all runs and the extraction recovery was >80%. The accuracy values for quality control samples varied from +3.6 to +9.7% and the inter-day precision (RSD %) values were ranged from 5.0 to 8.0%. The limit of detection was 1.0 ng/mL and the lower limit of quantification was 5 ng/mL utilizing methadone in human plasma samples. PMID:27566346

  2. Gel fire suppressants for controlling underground heating

    Institute of Scientific and Technical Information of China (English)

    HU Sheng-gen; XUE Sheng

    2011-01-01

    One of the major safety issues in coal mining is heatings and the resultant spontaneous combustion in underground coal mines.CSIRO researchers have developed a number of polymer gels suitable for controlling heatings in coal mines.These gels were developed to meet strict selection criteria including easy preparation,no or low toxicity,controllable gelation time,adaptable to mine water chemistry,adjustable viscosity,relatively long gel life,thermally and chemically stable and low cost.The HPAM-Aluminum Citrate gel system was identified to be the most favourable gel system for fire suppression in underground coal mines.These gels can be applied to the areas undergoing coal heating or gas leakage at a controllable gelation time and impermeable gel barriers can be formed in the areas to block ingress of air.

  3. Rheology of Biopolymer Solutions and Gels

    Directory of Open Access Journals (Sweden)

    David R. Picout

    2003-01-01

    Full Text Available Rheological techniques and methods have been employed for many decades in the characterization of polymers. Originally developed and used on synthetic polymers, rheology has then found much interest in the field of natural (bio polymers. This review concentrates on introducing the fundamentals of rheology and on discussing the rheological aspects and properties of the two major classes of biopolymers: polysaccharides and proteins. An overview of both their solution properties (dilute to semi-dilute and gel properties is described.

  4. Effect of sodium-alginate and laminaran on Salmonella Typhimurium infection in human enterocyte-like HT-29-Luc cells and BALB/c mice.

    Science.gov (United States)

    Kuda, Takashi; Kosaka, Misa; Hirano, Shino; Kawahara, Miho; Sato, Masahiro; Kaneshima, Tai; Nishizawa, Makoto; Takahashi, Hajime; Kimura, Bon

    2015-07-10

    Brown algal polysaccharides such as alginate, polymers of uronic acids, and laminaran, beta-1,3 and 1,6-glucan, can be fermented by human intestinal microbiota. To evaluate the effects of these polysaccharides on infections caused by food poisoning pathogens, we investigated the adhesion and invasion of pathogens (Salmonella Typhimurium, Listeria monocytogenes and Vibrio parahaemolyticus) in human enterocyte-like HT-29-Luc cells and in infections caused in BALB/c mice. Both sodium Na-alginate and laminaran (0.1% each) inhibited the adhesion of the pathogens to HT-29-Luc cells by approximately 70-90%. The invasion of S. Typhimurium was also inhibited by approximately 70 and 80% by Na-alginate and laminaran, respectively. We observed that incubation with Na-alginate for 18 h increased the transepithelial electrical resistance of HT-29-Luc monolayer cells. Four days after inoculation with 7 log CFU/mouse of S. Typhimurium, the faecal pathogen count in mice that were not fed polysaccharides (control mice) was about 6.5 log CFU/g while the count in mice that were fed Na-alginate had decreased to 5.0 log CFU/g. The liver pathogen count, which was 4.1 log CFU/g in the control mice, was also decreased in mice that were fed Na-alginate. In contrast, the mice that were fed laminaran exhibited a more severe infection than that exhibited by control mice.

  5. Ethanol fermentation of sugarcane molasses by Zymomonas mobilis MTCC 92 immobilized in Luffa cylindrica L. sponge discs and Ca-alginate matrices

    OpenAIRE

    Shuvashish Behera; Mohanty, Rama C.; Ray, Ramesh C.

    2012-01-01

    Bio-ethanol production from cane molasses (diluted to 15 % sugar w/v) was studied using the bacterium, Zymomonas mobilis MTCC 92 entrapped in luffa (Luffa cylindrica L.) sponge discs and Ca-alginate gel beads as the immobilizing matrices. At the end of 96 h fermentation, the final ethanol concentrations were 58.7 ± 0.09 and 59.1 ± 0.08 g/l molasses with luffa and Ca-alginate entrapped Z. mobilis cells, respectively exhibiting 83.25 ± 0.03 and 84.6 ± 0.02 % sugar conversion. There was no stati...

  6. THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

    Institute of Scientific and Technical Information of China (English)

    Qing-shan Kong; Bing-bing Wang; Quan Ji; Yan-zhi Xia; Zhao-xia Guo; Jian Yu

    2009-01-01

    Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride. The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry (TG), X-ray diffraction (XRD), limiting oxygen index (LOI) and cone calorimeter (CONE). The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34, and the heat release rate (HRR), total heat release (THR), CO and CO_2 concentrations during combustion are much lower compared with those of viscose fibers. Calcium carbonate and calcium oxide were formed during thermal degradation of calcium alginate fibers at different temperatures. The shape of calcium alginate fibers is well kept after LOI test. The rigid combustion residue char acts as an effective barrier to the outward diffusion of flame and heat. The combustion process and flame retardant mechanism of calcium alginate fibers are also discussed.

  7. Superabsorbing gel for actinide, lanthanide, and fission product decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Kaminski, Michael D.; Mertz, Carol J.

    2016-06-07

    The present invention provides an aqueous gel composition for removing actinide ions, lanthanide ions, fission product ions, or a combination thereof from a porous surface contaminated therewith. The composition comprises a polymer mixture comprising a gel forming cross-linked polymer and a linear polymer. The linear polymer is present at a concentration that is less than the concentration of the cross-linked polymer. The polymer mixture is at least about 95% hydrated with an aqueous solution comprising about 0.1 to about 3 percent by weight (wt %) of a multi-dentate organic acid chelating agent, and about 0.02 to about 0.6 molar (M) carbonate salt, to form a gel. When applied to a porous surface contaminated with actinide ions, lanthanide ions, and/or other fission product ions, the aqueous gel absorbs contaminating ions from the surface.

  8. A NOVEL BIO-WASTE INCORPORATED ALGINATE SORBENT FOR DE-FLUORIDATION OF WATER

    OpenAIRE

    Carmalin Sophia Ayyappan; Sreeja, S.; V.M. Bhalambaal

    2015-01-01

    This study evaluates the feasibility of using tamarind (Tamarindus indica) seed powder for de-fluoridation of fluoride contaminated water. Batch study confirmed that tamarind seeds in dry powder form could remove 87% of fluoride from water. This bio-sorbent can be used effectively in areas where fluoride concentrations are above the permissible limits of 1.5 mg·l-1 as per WHO Standard, 1984. Tamarind seed powder was incorporated in a matrix of sodium alginate and made into gel-beads. The bead...

  9. In vitro and in vivo Biocompatibility of Alginate Dialdehyde/Gelatin Hydrogels with and without Nanoscaled Bioactive Glass for Bone Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Ulrike Rottensteiner

    2014-03-01

    Full Text Available In addition to good mechanical properties needed for three-dimensional tissue engineering, the combination of alginate dialdehyde, gelatin and nano-scaled bioactive glass (45S5 is supposed to combine excellent cellular adhesion, proliferation and differentiation properties, good biocompatibility and predictable degradation rates. The goal of this study was to evaluate the in vitro and in vivo biocompatibility as a first step on the way to its use as a scaffold in bone tissue engineering. In vitro evaluation showed good cell adherence and proliferation of bone marrow derived mesenchymal stem cells seeded on covalently crosslinked alginate dialdehyde-gelatin (ADA-GEL hydrogel films with and without 0.1% nano-Bioglass® (nBG. Lactate dehydrogenase (LDH- and mitochondrial activity significantly increased in both ADA-GEL and ADA-GEL-nBG groups compared to alginate. However, addition of 0.1% nBG seemed to have slight cytotoxic effect compared to ADA-GEL. In vivo implantation did not produce a significant inflammatory reaction, and ongoing degradation could be seen after four weeks. Ongoing vascularization was detected after four weeks. The good biocompatibility encourages future studies using ADA-GEL and nBG for bone tissue engineering application.

  10. 21 CFR 184.1610 - Potassium alginate.

    Science.gov (United States)

    2010-04-01

    ...: Category of food Maximum level of use in food (as served) (percent) Functional use Confections and... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  11. 21 CFR 184.1133 - Ammonium alginate.

    Science.gov (United States)

    2010-04-01

    ...: Category of food Maximum level of use in food (as served) (percent) Functional use Confections, frostings... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium alginate. 184.1133 Section 184.1133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  12. An effective device for generating alginate microcapsules

    Directory of Open Access Journals (Sweden)

    Tatiana A.B. Bressel

    2008-01-01

    Full Text Available An alternative approach to somatic gene therapy is to deliver the therapeutic protein by implanting genetically modified cells that could overexpress the gene of interest. Microencapsulation devices were designed to protect cells from host rejection and prevent the foreign cells from spreading while allowing protein secretion. Alginate microcapsules form a semi-permeable structure that is suitable for in vivo injection. In this study, we report an effective laboratory protocol for producing calcium alginate microcapsules, following optimization of uniformly shaped and sized particles containing viable cells. Encapsulation of baby hamster kidney (BHK cells in alginate microcapsules was performed using a simple device consisting of a cylinder of compressed air and a peristaltic pump. A cell suspension flow of 100 mL h-1 and an air jet flow of 10 L min-1 produced the best uniformity of microcapsule size and shape. Cells maintained viability in culture for 4 weeks without any signs of necrosis, and protein diffusion was observed during this period. Our results clearly demonstrated that microisolation of BHK cells in alginate using a simple assembly device could provide an environment that is capable of preserving live cells. In addition, encapsulated cells under the conditions described were able to secrete an active enzyme even after four weeks, thus becoming potentially compatible with therapeutic protein delivery.

  13. Alginate encapsulated mesoporous silica nanospheres as a sustained drug delivery system for the poorly water-soluble drug indomethacin

    OpenAIRE

    Liang Hu; Changshan Sun; Aihua Song; Di Chang; Xin Zheng; Yikun Gao; Tongying Jiang; Siling Wang

    2014-01-01

    We applied a combination of inorganic mesoporous silica material, frequently used as drug carriers, and a natural organic polymer alginate (ALG), to establish a sustained drug delivery system for the poorly water-soluble drug Indomethacin (IND). Mesoporous silica nanospheres (MSNs) were synthesized using an organic template method and then functionalized with aminopropyl groups through postsynthesis. After drug loading into the pores of aninopropyl functionalized MSNs (AP-MSNs), IND loaded AP...

  14. Effect of the alkaline cation size on the conductivity in gel polymer electrolytes and their influence on photo electrochemical solar cells.

    Science.gov (United States)

    Bandara, T M W J; Fernando, H D N S; Furlani, M; Albinsson, I; Dissanayake, M A K L; Ratnasekera, J L; Mellander, B-E

    2016-04-28

    The nature and concentration of cationic species in the electrolyte exert a profound influence on the efficiency of nanocrystalline dye-sensitized solar cells (DSSCs). A series of DSSCs based on gel electrolytes containing five alkali iodide salts (LiI, NaI, KI, RbI and CsI) and polyacrylonitrile with plasticizers were fabricated and studied, in order to investigate the dependence of solar cell performance on the cation size. The ionic conductivity of electrolytes with relatively large cations, K(+), Rb(+) and Cs(+), was higher and essentially constant, while for the electrolytes containing the two smaller cations, Na(+) and Li(+), the conductivity values were lower. The temperature dependence of conductivity in this series appears to follow the Vogel-Tamman-Fulcher equation. The sample containing the smallest cation shows the lowest conductivity and the highest activation energy of ∼36.5 meV, while K(+), Rb(+) and Cs(+) containing samples show an activation energy of ∼30.5 meV. DSSCs based on the gel electrolyte and a TiO2 double layer with the N719 dye exhibited an enhancement in the open circuit voltage with increasing cation size. This can be attributed to the decrease in the recombination rate of electrons and to the conduction band shift resulting from cation adsorption by TiO2. The maximum efficiency value, 3.48%, was obtained for the CsI containing cell. The efficiencies shown in this study are lower compared to values reported in the literature, and this can be attributed to the use of a single salt and the absence of other additives, since the focus of the present study was to analyze the cation effect. The highest short circuit current density of 9.43 mA cm(-2) was shown by the RbI containing cell. The enhancement of the solar cell performance with increasing size of the cation is discussed in terms of the effect of the cations on the TiO2 anode and ion transport in the electrolyte. In liquid electrolyte based DSSCs, the short circuit current density

  15. Light-Addressable Electrodeposition of Magnetically-Guided Cells Encapsulated in Alginate Hydrogels for Three-Dimensional Cell Patterning

    Directory of Open Access Journals (Sweden)

    Shih-Hao Huang

    2014-11-01

    Full Text Available This paper describes a light-addressable electrolytic system used to perform an electrodeposition of magnetically-guided cells encapsulated in alginate hydrogels using a digital micromirror device (DMD for three-dimensional cell patterning. In this system, the magnetically-labeled cells were first manipulated into a specific arrangement by changing the orientation of the magnetic field, and then a patterned light illumination was projected onto a photoconductive substrate serving as a photo-anode to cause gelation of calcium alginate through sol-gel transition. By controlling the illumination pattern on the DMD, we first successfully produced cell-encapsulated multilayer alginate hydrogels with different shapes and sizes in each layer via performing multiplexed micropatterning. By combining the magnetically-labeled cells, light-addressable electrodeposition, and orientation of the magnetic fields, we have successfully demonstrated to fabricate two layers of the cell-encapsulated alginate hydrogels, where cells in each layer can be manipulated into cross-directional arrangements that mimic natural tissue. Our proposed method provides a programmable method for the spatiotemporally controllable assembly of cell populations into three-dimensional cell patterning and could have a wide range of biological applications in tissue engineering, toxicology, and drug discovery.

  16. Preparation and application of the sol-gel-derived acrylate/silicone co-polymer coatings for headspace solid-phase microextraction of 2-chloroethyl ethyl sulfide in soil.

    Science.gov (United States)

    Liu, Mingming; Zeng, Zhaorui; Fang, Huaifang

    2005-05-27

    Three types of novel acrylate/silicone co-polymer coatings, including co-poly(methyl acrylate/hydroxy-terminated silicone oil) (MA/OH-TSO), co-poly(methyl methacrylate/OH-TSO) (MMA/OH-TSO) and co-poly(butyl methacrylate/OH-TSO) (BMA/OH-TSO), were prepared for the first time by sol-gel method and cross-linking technology and subsequently applied to headspace solid-phase microextraction (HS-SPME) of 2-chloroethyl ethyl sulfide (CEES), a surrogate of mustard, in soil. The underlying mechanisms of the coating process were discussed and confirmed by IR spectra. The selectivity of the three types of sol-gel-derived acrylate/silicone coated fibers was studied, and the BMA/OH-TSO coated fibers exhibited the highest extraction ability to CEES. The concentration of BMA and OH-TSO in sol solution was optimized, and the BMA/OH-TSO (3:1)-coated fibers possessed the highest extraction efficiency. Compared with commercially available polyacrylate (PA) fiber, the sol-gel-derived BMA/OH-TSO (3:1) fibers showed much higher extraction efficiency to CEES. Therefore, the BMA/OH-TSO (3:1)-coated fibers were chosen for the analysis of CEES in soil matrix. The reproducibility of coating preparation was satisfactory, with the RSD 2.39% within batch and 3.52% between batches, respectively. The coatings proved to be quite stable at high temperature (to 350 degrees C) and in different solvents (organic or inorganic), thus their lifetimes (to 150 times) are longer than conventional fibers. Extraction parameters, such as the volume of water added to the soil, extraction temperature and time, and the ionic strength were optimized. The linearity was from 0.1 to 10 microg/g, the limit of detection (LOD) was 2.7 ng/g, and the RSD was 2.19%. The recovery of CEES was 88.06% in agriculture soil, 92.61% in red clay, and 101.95% in sandy soil, respectively.

  17. Incorporation of polydiacetylene sensors into commercial polymers

    Science.gov (United States)

    Kauffman, Jennifer Susan

    Polydiacetylenes (PDAs) exhibit a chromatic response to solvents, temperature, strain and other environmental perturbations. When formed in a solid-state polymerization, the backbone of the polymer is planar and continuous pi-overlap is observed. However, when the PDA backbone is distorted by an outside force the extended conjugation is interrupted and an optical shift from blue to red is observed. By exploiting the PDAs properties within polymer systems, smart fibers and films have been created that enhance the original intention of the host. Under this umbrella, a strain sensitive polydiacetylene-polyurethane blend was created using 3 and 4-butoxycarbonylmethylurethane PDA and a medical grade polyurethane, TecoflexRTM. Additionally, a temperature sensitive material has been developed with the renewable resource polymer, polylactic acid (PLA) blended with 10,12-pentacosadiynoic acid (PCDA). Finally, PCDA has been incorporated into sodium alginate to be used as environmentally responsive fibers. To match the aqueous solubility of the alginate, the PCDA was forced into a micellular structure through heating and probe sonication. After crystallization and polymerization, the water-soluble micelles were combined with the sodium alginate and wet-spun into calcium alginate "smart" fibers. The visual colorimetric detection (blue to red) was monitored optically and quantitatively by absorbance and Raman spectroscopy.

  18. Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography

    International Nuclear Information System (INIS)

    The purpose of this study was to compare characteristics of radiochromic gel – Turnbull Blue gel (TB gel) with polymer gel – polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0–15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV–vis Spectrophotometer Helios β and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. - highlights: • Gel dosimeters are suitable for steep dose gradient verification. • An optical tomography evaluation method is successful. • Dose response characteristics of TB gel and PAGAT gel are presented

  19. Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography

    Science.gov (United States)

    Pilařová (Vávrů), Kateřina; Kozubíková, Petra; Šolc, Jaroslav; Spěváček, Václav

    2014-11-01

    The purpose of this study was to compare characteristics of radiochromic gel - Turnbull Blue gel (TB gel) with polymer gel - polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0-15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV-vis Spectrophotometer Helios β and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. Gel dosimeters are suitable for steep dose gradient verification. An optical tomography evaluation method is successful. Dose response characteristics of TB gel and PAGAT gel are presented.

  20. Time-Dependent Effect of Encapsulating Alginate Hydrogel on Neurogenic Potential

    Science.gov (United States)

    Razavi, Shahnaz; Khosravizadeh, Zahra; Bahramian, Hamid; Kazemi, Mohammad

    2015-01-01

    Objective Due to the restricted potential of neural stem cells for regeneration of central nervous system (CNS) after injury, providing an alternative source for neural stem cells is essential. Adipose derived stem cells (ADSCs) are multipotent cells with properties suitable for tissue engineering. In addition, alginate hydrogel is a biocompatible polysaccharide polymer that has been used to encapsulate many types of cells. The aim of this study was to assess the proliferation rate and level of expression of neural markers; NESTIN, glial fibrillary acidic protein (GFAP) and microtubule-associated protein 2 (MAP2) in encapsulated human ADSCs (hADSCs) 10 and14 days after neural induction. Materials and Methods In this experimental study, ADSCs isolated from human were cultured in neural induction media and seeded into alginate hydrogel. The rate of proliferation and differentiation of encapsulated cells were evaluated by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) assay, immunocytoflourescent and realtime reverse transcriptase polymerase chain reaction (RT-PCR) analyzes 10 and 14 days after induction. Results The rate of proliferation of encapsulated cells was not significantly changed with time passage. The expression of NESTIN and GFAP significantly decreased on day 14 relative to day 10 (P<0.001) but MAP2 expression was increased. Conclusion Alginate hydrogel can promote the neural differentiation of encapsulated hADSCs with time passage. PMID:26199909

  1. Studies of magnetic alginate-based electrospun matrices crosslinked with different methods for potential hyperthermia treatment.

    Science.gov (United States)

    Chen, Yen-Hsuan; Cheng, Chi-Hui; Chang, Wan-Ju; Lin, Yi-Ching; Lin, Feng-Huei; Lin, Jui-Che

    2016-05-01

    The magnetic electrospun mats were lately established as an innovative biomaterial for hyperthermic cancer treatment. Unlike those surface-modified magnetic nanoparticles that may not firmly adhere onto the tumor for long-term duration, the magnetic mats with nanofibrous structure can promote cell adhesion and kill the tumor directly within an alternating magnetic field. However, most magnetic electrospun mats were fabricated using non-biodegradable polymers and organic solvents, causing the problems of removal after therapy and the suspected biotoxicity associated with residual solvent. Alginate (SA) was utilized in this investigation as the main material for electrospinning because of being biodegradable and water-soluble. The alginate-based electrospun mats were then treated by an ionic or a covalent crosslinking method, and then followed by chelation with Fe(2+)/Fe(3+) for chemical coprecipitation of Fe3O4 magnetic nanoparticles. Significant less cytotoxicity was noted on both liquid extracts from the ionic-crosslinked (Fe3O4-SA/PEO) and covalent-crosslinked (Fe3O4-SA/PVA) magnetic electrospun mats as well as the surface of Fe3O4-SA/PVA. In vitro hyperthermia assay indicated that the covalent-crosslinked magnetic alginate-based mats reduced tumor cell viability greater than Fe3O4 nanoparticles. Such magnetic electrospun mats are of potential for hyperthermia treatment by endoscopic/surgical delivery as well as serving as a supplementary debridement treatment after surgical tumor removal. PMID:26952432

  2. Active Gel Model of Amoeboid Cell Motility

    CERN Document Server

    Callan-Jones, A C

    2013-01-01

    We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-susbstrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.

  3. Modification of Cellulose Products by the Use of Chitosan and Chitosan-Alginate Nano-Particles

    Directory of Open Access Journals (Sweden)

    Brzoza-Malczewska Kinga

    2016-03-01

    Full Text Available Aim of the presented research was the improvement of fibrous cellulosic products for uses in hygiene and medical sectors. Nano-particles of bioactive polysaccharides were imparted to cellulosic fibrous products to modify their properties: physical–chemical like absorption, biological like antibacterial and antifungal activity, and mechanical. Fibrous materials like dressing gauze, wood-wool, and hygiene tissues were modified by the addition of chitosan and chitosan-alginate nano-particles. Padding and freeze-drying was applied in the coating of the fibrous materials with the nano-sized polymers.

  4. PREPARATION AND EVALUATION OF SUSTAINED RELEASE MICROSPHERE OF NORFLOXACIN USING SODIUM ALGINATE

    Directory of Open Access Journals (Sweden)

    Raja Chakraverty

    2012-01-01

    Full Text Available Oral controlled drug delivery systems represent the most popular form of sustained drug delivery systems for the obvious advantages of oral route of drug administration. Such systems release the drug with constant or variable release rates. The oral controlled release systems shows a typical pattern of drug release in which the drug concentration is maintained in the therapeutic window for a prolonged period of time (sustained release, thereby ensuring sustained therapeutic action. They are used as single dosage form. Present work involves preparation and evaluation of sustained release of microspheres of Norfloxacin employing sodium alginate as natural polymer. The technique employed for microencapsulation of the drug is ionotropic gelation.

  5. Preparation of monolithic molecularly imprinted polym