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Sample records for alginic acid aa

  1. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  2. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1011 Alginic acid. (a) Alginic acid is a colloidal, hydrophilic polysaccharide obtained from...

  3. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  4. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  5. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  6. Alginic Acid Accelerates Calcite Dissolution

    NASA Astrophysics Data System (ADS)

    Perry, T. D.; Duckworth, O. W.; McNamara, C. J.; Martin, S. T.; Mitchell, R.

    2003-12-01

    Accelerated carbonate weathering through biological activity affects both geochemical cycling and the local pH and alkalinity of terrestrial and marine waters. Microbes affect carbonate dissolution through metabolic activity, production of acidic or chelating exudates, and cation binding by cell walls. Dissolution occurs within microbial biofilms - communities of microorganisms attached to stone in an exopolymer matrix. We investigated the effect of alginic acid, a common biological polymer produced by bacteria and algae, on calcite dissolution using a paired atomic force microscopy/flow-through reactor apparatus. The alginic acid caused up to an order of magnitude increase in dissolution rate at 3 < pH < 12. Additionally, the polymer preferentially binds to the obtuse pit steps and increases step velocity. We propose that the polymer is actively chelating surficial cations reducing the activation energy and increasing dissolution rate. The role of biologically produced polymers in mineral weathering is important in the protection of cultural heritage materials and understanding of marine and terrestrial systems.

  7. Biocompatibility of mannuronic acid-rich alginates.

    PubMed

    Klöck, G; Pfeffermann, A; Ryser, C; Gröhn, P; Kuttler, B; Hahn, H J; Zimmermann, U

    1997-05-01

    Highly purified algin preparations free of adverse contaminants with endotoxins and other mitogens recently became available by a new purification process (Klöck et al., Appl. Microbiol. Biotechnol., 1994, 40, 638-643). An advantage of this purification protocol is that it can be applied to alginates with various ratios of mannuronic acid to guluronic acid. High mannuronic acid alginate capsules are of particular practical interest for cell transplantation and for biohybrid organs, because mannuronate-rich alginates are usually less viscous, allowing one to make gels with a higher alginate content. This will increase their stability and reduce the diffusion permeability and could therefore protect immobilized cells more efficiently against the host immune system. Here we report the biocompatibility of purified, mannuronic acid-rich alginate (68% mannuronate residues) in a series of in vitro, as well as in vivo, assays. In contrast to raw alginate extracts, the purified product showed no mitogenic activity towards murine lymphocytes in vitro. Its endotoxin content was reduced to the level of the solvent. Animal studies with these new, purified algin formulations revealed the absence of a mitogen-induced foreign body reaction, even when the purified material (after cross-linking with Ba2+ ions) is implanted into animal models with elevated macrophage activity (diabetes-prone BB/OK rat). Thus, alginate capsules with high mannuronic acid content become available for applications such as implantation. In addition to the utilization as implantable cell reactors in therapy and biotechnology, these purified algins have broad application potential as ocular fillings, tissue replacements, microencapsulated growth factors and/or interleukins or slow-release dosage forms of antibodies, surface coatings of sensors and other invasive medical devices, and in encapsulation of genetically engineered cells for gene therapy.

  8. Performance of alginate films for retention of L-(+)-ascorbic acid.

    PubMed

    De'Nobili, M D; Curto, L M; Delfino, J M; Soria, M; Fissore, E N; Rojas, A M

    2013-06-25

    In view of acting as controlled delivery systems for nutritional supplementation, therapy or antioxidant activity at interfaces, alginate films of different copolymer composition and glycerol plasticizer levels were developed in the presence of Ca(2+) for achieving higher stability of L-(+)-ascorbic acid (AA). The ability of the alginate network to preserve AA from hydrolysis, tested by storage under vacuum at 25 °C, only decreased with the relative humidity (RH) increase when alginates were mainly constituted by guluronic-guluronic acid blocks (GG), whereas also decreased with the glycerol level increase when mannuronic-mannuronic acid (MM) and/or alternating guluronic-mannuronic (GM+MG) flexible blocks were present in higher proportions. This result could be probably related to the lower capability of the latter alginate block compositions to immobilize water in the network as they are not able to constitute Ca(2+) mediated junction zones where water molecules are highly retained. Films also studied under air storage showed that even at less favorable conditions of RH and glycerol levels, both GG and GM+MG enriched alginate networks in general preserved AA from oxidation. It also demonstrated that hydrolysis is the principal way by which AA is lost when supported in films.

  9. Reduction of hypervalent chromium in acidic media by alginic acid.

    PubMed

    Bertoni, Fernando A; Bellú, Sebastian E; González, Juan C; Sala, Luis F

    2014-12-19

    Selective oxidation of carboxylate groups present in alginic acid by Cr(VI) affords CO2, oxidized alginic acid, and Cr(III) as final products. The redox reaction afforded first-order kinetics in [alginic acid], [Cr(VI)], and [H(+)], at fixed ionic strength and temperature. Kinetic studies showed that the redox reaction proceeds through a mechanism which combines Cr(VI)→Cr(IV)→Cr(II) and Cr(VI)→Cr(IV)→Cr(III) pathways. The mechanism was supported by the observation of free radicals, CrO2(2+) and Cr(V) as reaction intermediates. The reduction of Cr(IV) and Cr(V) by alginic acid was independently studied and it was found to occur more than 10(3) times faster than alginic acid/Cr(VI) reaction, in acid media. At pH 1-3, oxo-chromate(V)-alginic acid species remain in solution during several hours at 15°C. The results showed that this abundant structural polysaccharide present on brown seaweeds is able to reduce Cr(VI/V/IV) or stabilize high-valent chromium depending on pH value.

  10. Antibacterial performance of alginic acid coating on polyethylene film.

    PubMed

    Karbassi, Elika; Asadinezhad, Ahmad; Lehocký, Marian; Humpolíček, Petr; Vesel, Alenka; Novák, Igor; Sáha, Petr

    2014-08-21

    Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance.

  11. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    NASA Astrophysics Data System (ADS)

    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 %.

  12. Maximization of volatile fatty acids production from alginate in acidogenesis.

    PubMed

    Pham, Hong Duc; Seon, Jiyun; Lee, Seong Chan; Song, Minkyung; Woo, Hee-Chul

    2013-11-01

    In this study, the response surface methodology (RSM) was applied to determine the optimum fermentative condition of alginate with the respect to the simultaneous effects of alginate concentration and initial pH to maximize the production of total volatile fatty acids (TVFAs) and alcohols. The results showed that the alginate fermentation was significantly affected by initial pH than by alginate concentration and there was no interaction between the two variables. The optimum condition was 6.2g alginate/L and initial pH 7.6 with a maximum TVFAs yield of 37.1%. Acetic acids were the main constituents of the TVFAs mixtures (i.e., 71.9-95.5%), while alcohols (i.e., ethanol, butanol, and propanol) were not detected.

  13. Chemical modification of alginic acid by ultrasonic irradiation

    NASA Astrophysics Data System (ADS)

    Murdzheva, Dilyana; Denev, Panteley

    2016-03-01

    Abstract: Chemical modification of alginic acid has been done by ultrasonic irradiation to obtain its methylated, ethylated and isopropylated derivatives. The influence of ultrasonic frequency and power on esterification process of alginic acid has been investigated. Alginate derivatives have been characterized by degree of esterification (DE) and IR-FT spectroscopy. It has been found that 45 kHz ultrasonic frequency accelerated modification process as reduced the reaction time from 16 hours to 2 hours. The obtained results showed that ultrasound irradiation increased the reaction efficiency in methanol and depended on the ratio of the M/G.

  14. Micellar electrokinetic capillary chromatography determination of alginic acid in pharmaceutical formulations after treatment with alginate lyase and UV detection.

    PubMed

    Volpi, Nicola

    2008-09-01

    A new highly specific and sensitive capillary electrophoresis method (electrokinetic chromatography with SDS) for the determination of the total alginic acid (AA) content in pharmaceutical formulations is described by means of capillary electrophoresis at 230 nm after treatment with alginate lyase [4.2.2.3] and separation of unsaturated products, Delta-oligomers (DeltaHexA-[HexA](n)), in particular, DP3 (DeltaHexA-HexA-HexA) and DP4 (DeltaHexA-HexA-HexA-HexA). Using a buffer constituted with 10 mM sodium borate and 50 mM SDS at pH 9.0, micellar electrokinetic capillary chromatography was able to determine with very high resolution the AA Delta-oligomers produced by the action of the lyase (mainly DP3 and DP4) as one single species. The intra- and inter-day variations (CV%) were between 6.3 and 9.1 for migration time and between 2.5 and 5.7 for peak area, respectively. The calibration curve showed good linearity for the examined concentration range (60-360 ng) with an average correlation coefficient greater than 0.980. The lowest detection limit and the lowest quantitation limit of the method were 15 ng (0.25 mg/mL) and 40 ng (0.67 mg/mL), respectively. The intra- and inter-day variations in terms of CV% were 5.5 and 8.6%, respectively, and the intra- and inter-day accuracy was estimated to range from 4.1 to 8.9%, while the percent recoveries of AA were calculated to be 102, 97 and 93% for different AA amounts. Variations in temperatures, voltage and buffer composition in comparison with adopted conditions within a 10% limit do not modify the electrophoresis results. The evaluation of AA was performed in both solid and liquid pharmaceutical formulations also in the presence of other ingredients, in particular, aluminium, sodium and potassium bicarbonate, and emulsifying and flavouring agents. The quantitative results obtained were 101.2+/-3.4% of AA content in tablets and 98.4+/-2.8% in liquid formulation, in total conformity with the label claims.

  15. Small-angle X-ray scattering and rheological characterization of alginate gels. 3. Alginic acid gels.

    PubMed

    Draget, Kurt Ingar; Stokke, Bjørn T; Yuguchi, Yoshiaki; Urakawa, Hiroshi; Kajiwara, Kanji

    2003-01-01

    Alginic acid gels were studied by small-angle X-ray scattering and rheology to elucidate the influence of alginate chemical composition and molecular weight on the gel elasticity and molecular structure. The alginic acid gels were prepared by homogeneous pH reduction throughout the sample. Three alginates with different chemical composition and sequence, and two to three different molecular weights of each sample were examined. Three alginate samples with fractions of guluronic acid residues of 0.39 (LoG), 0.50 (InG), and 0.68 (HiG), covering the range of commercially available alginates, were employed. The excess scattering intensity I of the alginic acid gels was about 1 order of magnitude larger and exhibited a stronger curvature toward low q compared to ionically cross-linked alginate. The I(q) were decomposed into two components by assuming that the alginic acid gel is composed of aggregated multiple junctions and single chains. Time-resolved experiments showed a large increase in the average size of aggregates and their weight fraction within the first 2 h after onset of gelling, which also coincides with the most pronounced rheological changes. At equilibrium, little or no effect of molecular weight was observed, whereas at comparable molecular weights, an increased scattering intensity with increasing content of guluronic acid residues was recorded, probably because of a larger apparent molecular mass of domains. The results suggest a quasi-ordered junction zone is formed in the initial stage, followed by subsequent assembling of such zones, forming domains in the order of 50 A. The average length of the initial junction zones, being governed by the relative fraction of stabilizing G-blocks and destabilizing alternating (MG) blocks, determines the density of the final random aggregates. Hence, high-G alginates give alginic acid gels of a higher aggregate density compared to domains composed of loosely packed shorter junction zones in InG or LoG system.

  16. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes.

    PubMed

    Kim, Han-Sem; Song, Minsoo; Lee, Eun-Jung; Shin, Ueon Sang

    2015-06-01

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H3PO4/P2O5/Et3PO4 followed by acid-base reaction with Ca(OAc)2 to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for (1)H, and (31)P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2w/v%) with NaAlg solution (2w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO4 or CaCl2 were added externally. The gelation was completed within about 3-40min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤6.7kPa for compressive strength at break and about 8.4kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100-800μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering.

  17. Insulin-loaded alginic acid nanoparticles for sublingual delivery.

    PubMed

    Patil, Nilam H; Devarajan, Padma V

    2016-01-01

    Alginic acid nanoparticles (NPs) containing insulin, with nicotinamide as permeation enhancer were developed for sublingual delivery. The lower concentration of proteolytic enzymes, lower thickness and enhanced retention due to bioadhesive property, were relied on for enhanced insulin absorption. Insulin-loaded NPs were prepared by mild and aqueous based nanoprecipitation process. NPs were negatively charged and had a mean size of ∼200 nm with low dispersity index. Insulin loading capacities of >95% suggested a high association of insulin with alginic acid. Fourier Transform Infra-Red Spectroscopy (FTIR) spectra and DSC (Differential Scanning Calorimetry) thermogram of insulin-loaded NPs revealed the association of insulin with alginic acid. Circular dichroism (CD) spectra confirmed conformational stability, while HPLC analysis confirmed chemical stability of insulin in the NPs. Sublingually delivered NPs with nicotinamide exhibited high pharmacological availability (>100%) and bioavailability (>80%) at a dose of 5 IU/kg. The high absolute pharmacological availability of 20.2% and bioavailability of 24.1% in comparison with subcutaneous injection at 1 IU/kg, in the streptozotocin-induced diabetic rat model, suggest the insulin-loaded alginic acid NPs as a promising sublingual delivery system of insulin.

  18. Preparation of alginate beads containing a prodrug of diethylenetriaminepentaacetic acid

    PubMed Central

    Yang, Yu-Tsai; Di Pasqua, Anthony J.; He, Weiling; Tsai, Tsuimin; Sueda, Katsuhiko; Zhang, Yong; Jay, Michael

    2012-01-01

    A penta-ethyl ester prodrug of the radionuclide decorporation agent diethylenetriaminepentaacetic acid (DTPA), which exists as an oily liquid, was encapsulated in alginate beads by the ionotropic gelation method. An optimal formulation was found by varying initial concentrations of DTPA pentaethyl ester, alginate polymer, Tween 80 surfactant and calcium chloride. All prepared alginate beads were ~1.6 mm in diameter, and the optimal formulation had loading and encapsulation efficiencies of 91.0 ± 1.1 and 72.6 ± 2.2%, respectively, and only 3.2 ± 0.8% water absorption after storage at room temperature in ~80% relative humidity. Moreover, Fourier transform infrared spectroscopy showed that DTPA penta-ethyl ester did not react with excipients during formation of the DTPA penta-ethyl ester-containing alginate beads. Release of prodrug from alginate beads was via anomalous transport, and its stability enhanced by encapsulation. Collectively, these data suggest that this solid dosage form may be suitable for oral administration after radionuclide contamination. PMID:23399237

  19. Fabrication and characterization of chitosan-crosslinked-poly(alginic acid) nanohydrogel for adsorptive removal of Cr(VI) metal ion from aqueous medium.

    PubMed

    Sharma, Gaurav; Naushad, Mu; Al-Muhtaseb, Ala'a H; Kumar, Amit; Khan, Mohammad Rizwan; Kalia, Susheel; Shweta; Bala, Manju; Sharma, Arush

    2017-02-01

    In this study, chitosan-crosslinked-poly (alginic acid) nanohydrogel (CN-cl-PL(AA)NHG) was synthesized by co-polymerization method. It was used an effective adsorbent for the exclusion of Cr(VI) metal ion from aqueous medium. The synthesized nanohydrogel was characterized by FTIR, SEM and TEM. The TEM images clearly indicated the appearance of smooth surface with average size of particles ranging from 30 to 80nm. The effect of different adsorption parameters like agitation time, temperature, initial metal ion concentration and adsorbent dosage was studied and optimized. The results demonstrated that the prepared chitosan-crosslinked-poly (alginic acid) nanohydrogel had high adsorption tendency for the removal of Cr(VI) from the aqueous solution. The pseudo-second-order equation represented the better adsorption kinetics for the adsorption process. The thermodynamic studies showed the adsorption of Cr(VI) onto CN-cl-PL(AA)NHG was spontaneous and chemical in nature.

  20. Solubilizing carbon nanotubes through noncovalent functionalization. Insight from the reversible wrapping of alginic acid around a single-walled carbon nanotube.

    PubMed

    Liu, Yingzhe; Chipot, Christophe; Shao, Xueguang; Cai, Wensheng

    2010-05-06

    Carbon nanotubes coated with alginic acid (AA) through noncovalent functionalization have been shown to be soluble and dispersed in water. In the present contribution, all-atom molecular dynamics simulations have been performed to probe the self-assembly mechanism that underlies the formation of complexes by AA and a single-walled carbon nanotube (SWCNT), both in the gas phase and in an aqueous solution. Results of these simulations reveal that AA can wrap around SWCNT by virtue of van der Waals attractions and organize into a compact helical structure, a process induced in the gas phase by hydrogen-bonding interactions. In contrast, in an alginate aqueous solution, a loose helical wrapping mode is found to be favored by virtue of electrostatic repulsions in conjunction with the weakening of hydrogen-bonding interactions. Documented experimentally (Liu, Y.; et al. Small 2006, 2, 874-878) and coined "Great Wall of China" motif, the typical arrangement of AA residues around the tubular structure, conducive to dissolve nanotubes, is observed in the present simulations. Investigation of metal cations binding to AA suggests that calcium ions can mediate aggregation of AA chains by interacting strongly with the carboxylate groups, thereby leading to reverse unwrapping. The results reported in this work shed meaningful light on the potential of noncovalent functionalization for solubilizing carbon nanotubes, and open exciting perspectives for the design of new wrapping agents that are envisioned to form the basis of innovative nanomaterials targeted at chemical and biomedical applications.

  1. Effects of the biologically produced polymer alginic acid on macroscopic and microscopic calcite dissolution rates.

    PubMed

    Perry, Thomas D; Duckworth, Owen W; McNamara, Christopher J; Martin, Scot T; Mitchell, Ralph

    2004-06-01

    Dissolution of carbonate minerals has significant environmental effects. Microorganisms affect carbonate dissolution rates by producing extracellular metabolites, including complex polysaccharides such as alginic acid. Using a combined atomic force microscopy (AFM)/flowthrough reactor apparatus, we investigated the effects of alginic acid on calcite dissolution. Macroscopic dissolution rates, derived from the aqueous metal ion concentrations, are 10(-5.5) mol m(-2) s(-1) for 5 < pH < 12 in the absence of alginic acid compared to 10(-4.8) mol m(-2) s(-1) in its presence. The AFM images demonstrate that alginic acid preferentially attacks the obtuse steps of dissolution pits on the calcite surface. In pure water, the obtuse and acute steps retreat at similar rates, and the pits are nearly isotropic except under highly acidic conditions. In alginic acid, the acute step retreat rate is nearly unchanged in comparison to water, whereas the obtuse step retreat rate increases with decreasing pH values. As a result, the pits remain rhombohedral but propagate faster in the obtuse direction. To explain these observations, we propose that alginic acid preferentially forms dissolution active surface complexes with calcium atoms on the obtuse step, which results in anisotropic ligand-promoted dissolution.

  2. Combinatory approach of methacrylated alginate and acid monomers for concrete applications.

    PubMed

    Mignon, Arn; Devisscher, Dries; Graulus, Geert-Jan; Stubbe, Birgit; Martins, José; Dubruel, Peter; De Belie, Nele; Van Vlierberghe, Sandra

    2017-01-02

    Polysaccharides, and especially alginate, can be useful for self-healing of cracks in concrete. Instead of weak electrostatic bonds present within calcium alginate, covalent bonds, by methacrylation of the polysaccharides, will result in mechanically stronger superabsorbent polymers (SAPs). These methacrylated alginate chains as backbone are combined with two acrylic monomers in a varying molar fraction. These SAPs show a moisture uptake capacity up to 110% their own weight at a relative humidity of 95%, with a negligible hysteresis. The swelling capacity increased (up to 246 times its own weight) with a decreasing acrylic acid/2 acrylamido-2-methylpropane sulfonic acid ratio. The SAPs also showed a thermal stability up to 200°C. Interestingly, the SAP composed of alginate and acrylic acid exerted a very limited decrease in compressive strength (up to 7% with addition of 1wt% SAP) rendering this material interesting for the envisaged self-healing application.

  3. Efficacy of acidic pretreatment for the saccharification and fermentation of alginate from brown macroalgae.

    PubMed

    Wang, Damao; Yun, Eun Ju; Kim, Sooah; Kim, Do Hyoung; Seo, Nari; An, Hyun Joo; Kim, Jae-Han; Cheong, Nam Yong; Kim, Kyoung Heon

    2016-06-01

    This study was performed to evaluate the effectiveness of acidic pretreatment in increasing the enzymatic digestibility of alginate from brown macroalgae. Pretreatment with 1 % (w/v) sulfuric acid at 120 °C for 30 min produced oligosaccharides, mannuronic acid, and guluronic acid. Enzymatic saccharification of pretreated alginate by alginate lyases produced 52.2 % of the theoretical maximal sugar yield, which was only 7.5 % higher than the sugar yield obtained with unpretreated alginate. Mass spectrometric analyses of products of the two reactions revealed that acidic pretreatment and enzymatic saccharification produced saturated monomers (i.e., mannuronic and guluronic acid) with saturated oligosaccharides and unsaturated monomers (i.e., 4-deoxy-L-erythro-5-hexoseulose uronic acid; DEH), respectively. While DEH is further metabolized by microorganisms, mannuronic acid and guluronic acid are not metabolizable. Because of the poor efficacy in increasing enzymatic digestibility and owing to the formation of non-fermentable saturated monomers, acidic pretreatment cannot be recommended for enzymatic saccharification and fermentation of alginate.

  4. Swelling assisted photografting of itaconic acid onto sodium alginate membranes

    NASA Astrophysics Data System (ADS)

    Taşkın, Gülşen; Şanlı, Oya; Asman, Gülsen

    2011-09-01

    Grafting of itaconic acid (IA) was achieved onto sodium alginate (NaAlg) membranes by using UV-radiation. Process was performed under nitrogen atmosphere and benzophenone (BP) was used as a photoinitiator. Membranes were preswelled before the polymerization process and ethanol was determined as the best swelling agent among the studied solvents. The effect of polymerization time, initiator and monomer concentrations on the grafting efficiency were investigated. The best conditions for optimum grafting were obtained with IA concentration of 1.0 M, a BP concentration of 0.1 M and a reaction time of 4 h at 25 °C. Under these conditions grafting efficiency for NaAlg-g-IA membranes was found to be 14% (w/w). To obtain further increase in grafting efficiency membranes were also preswelled in IA and BP solutions and polymerization was carried out at different temperatures after UV polymerization. Grafted membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Effect of grafting on membrane properties such as intrinsic viscosity and swelling percentage were also determined.

  5. Immobilization of urease by using chitosan-alginate and poly(acrylamide-co-acrylic acid)/kappa-carrageenan supports.

    PubMed

    Kara, Filiz; Demirel, Gökhan; Tümtürk, Hayrettin

    2006-08-01

    Jack bean urease (urea aminohydrolase, E.C. 3.5.1.5) was entrapped into chitosan-alginate polyelectrolyte complexes (C-A PEC) and poly(acrylamide-co-acrylic acid)/kappa-carrageenan (P(AAm-co-AA)/carrageenan) hydrogels for the potential use in immobilization of urease, not previously reported. The effects of pH, temperature, storage stability, reuse number, and thermal stability on the free and immobilized urease were examined. For the free and immobilized urease into C-A PEC and P(AAm-co-AA)/carrageenan, the optimum pH was found to be 7.5 and 8, respectively. The optimum temperature of the free and immobilized enzymes was also observed to be 55 and 60 degrees C, respectively. Michaelis-Menten constant (K(m)) values for both immobilized urease were also observed smaller than free enzyme. The storage stability values of immobilized enzyme systems were observed as 48 and 70%, respectively, after 70 days. In addition to this, it was observed that, after 20th use in 5 days, the retained activities for immobilized enzyme into C-A PEC and P(AAm-co-AA)/carrageenan matrixes were found as 55 and 89%, respectively. Thermal stability of the free urease was also increased by a result of immobilization.

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

    PubMed

    Mandal, Bidyadhar; Ray, Samit Kumar

    2013-10-15

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

  7. Efficiency of uronic acid uptake in marine alginate-degrading fungi

    NASA Astrophysics Data System (ADS)

    Schaumann, K.; Weide, G.

    1995-03-01

    Despite the fact that many marine fungi, including phycomycetes, yeasts, ascomycetes and hyphomycetes, have been recorded from living and/or dead phaeophytes, only a few of these have been shown to be capable of degrading alginic acid or alginates. The degradation is achieved by the action of an exoenzyme complex, comprising alginate lyase, as well as alginate hydrolase activities. The latter was detected only recently by the authors. In this study, the growth of two marine sodiumalginate-degrading deuteromycetes, Asteromyces cruciatus and Dendryphiella salina, was investigated, and the assimilation efficiency of sodiumalginate and its uronic acid degradation products, respectively, was estimated from the economic coefficient (E). E is calculated from the mycelial dry weight, divided by the weight of substrate consumed for this production. The economic coefficient for A. cruciatus was 48.6%, and that of D. salina 38.9%. This indicates that the former species uses the alginate degradation products more efficiently than the latter. The observed E-values for the marine deuteromycetes agree with those from other fungi, e.g. terrestrial species. In general, it is concluded that the marine fungi appear to play a more important role in kelp-based ecosystems than was realized previously.

  8. Boronic acid-modified alginate enables direct formation of injectable, self-healing and multistimuli-responsive hydrogels.

    PubMed

    Pettignano, Asja; Grijalvo, Santiago; Häring, Marleen; Eritja, Ramon; Tanchoux, Nathalie; Quignard, Françoise; Díaz Díaz, David

    2017-03-16

    One-step functionalization of alginate with boronic acid groups allowed spontaneous formation of biocompatible hydrogels under basic conditions without additional complementary molecules or crosslinking agents. The dynamic nature of boronate ester bonds formed with vicinal diols present on alginate pyranose rings provided remarkable self-healing, injectable and multi-stimuli responsive properties to the material.

  9. Novel crosslinked alginate/hyaluronic acid hydrogels for nerve tissue engineering

    NASA Astrophysics Data System (ADS)

    Wang, Min-Dan; Zhai, Peng; Schreyer, David J.; Zheng, Ruo-Shi; Sun, Xiao-Dan; Cui, Fu-Zhai; Chen, Xiong-Biao

    2013-09-01

    Artificial tissue engineering scaffolds can potentially provide support and guidance for the regrowth of severed axons following nerve injury. In this study, a hybrid biomaterial composed of alginate and hyaluronic acid (HA) was synthesized and characterized in terms of its suitability for covalent modification, biocompatibility for living Schwann cells and feasibility to construct three dimensional (3D) scaffolds. Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calciumions that ionically crosslink alginate. Amide formation was found to be dependent on the concentrations of carbodiimide and calcium chloride. The double-crosslinked composite hydrogels display biocompatibility that is comparable to simple HA hydrogels, allowing for Schwann cell survival and growth. No significant difference was found between composite hydrogels made from different ratios of alginate and HA. A 3D BioPlotter™ rapid prototyping system was used to fabricate 3D scaffolds. The result indicated that combining HA with alginate facilitated the fabrication process and that 3D scaffolds with porous inner structure can be fabricated from the composite hydrogels, but not from HA alone. This information provides a basis for continuing in vitro and in vivo tests of the suitability of alginate/HA hydrogel as a biomaterial to create living cell scaffolds to support nerve regeneration.

  10. Structure of a Bacterial ABC Transporter Involved in the Import of an Acidic Polysaccharide Alginate.

    PubMed

    Maruyama, Yukie; Itoh, Takafumi; Kaneko, Ai; Nishitani, Yu; Mikami, Bunzo; Hashimoto, Wataru; Murata, Kousaku

    2015-09-01

    The acidic polysaccharide alginate represents a promising marine biomass for the microbial production of biofuels, although the molecular and structural characteristics of alginate transporters remain to be clarified. In Sphingomonas sp. A1, the ATP-binding cassette transporter AlgM1M2SS is responsible for the import of alginate across the cytoplasmic membrane. Here, we present the substrate-transport characteristics and quaternary structure of AlgM1M2SS. The addition of poly- or oligoalginate enhanced the ATPase activity of reconstituted AlgM1M2SS coupled with one of the periplasmic solute-binding proteins, AlgQ1 or AlgQ2. External fluorescence-labeled oligoalginates were specifically imported into AlgM1M2SS-containing proteoliposomes in the presence of AlgQ2, ATP, and Mg(2+). The crystal structure of AlgQ2-bound AlgM1M2SS adopts an inward-facing conformation. The interaction between AlgQ2 and AlgM1M2SS induces the formation of an alginate-binding tunnel-like structure accessible to the solvent. The translocation route inside the transmembrane domains contains charged residues suitable for the import of acidic saccharides.

  11. Forward osmosis filtration for removal of organic foulants: Effects of combined tannic and alginic acids.

    PubMed

    Wang, Lin; Zhang, Wanzhu; Chu, Huaqiang; Dong, Bingzhi

    2016-03-15

    The filtration performance of combined organic foulants by forward osmosis (FO) in active-layer-facing-the-draw-solution (AL-facing-DS) orientation was investigated systematically. Tannic acid and alginate were used as model organic foulants for polysaccharides and humic dissolved organic matters, respectively. The FO could reject combined and single tannic acid and alginate foulants effectively. The more severe fouling flux decline, accompanied with lower combined foulants' retention, was observed with increasing proportions of tannic acid in the combined foulants-containing feed, which was ascribed mainly to the more severe fouling resulting from tannic acid adsorption within the porous support layer of the FO membrane compared to minor alginate deposition on the membrane surface. It was found that the higher the initial flux level and cross flow velocity, the faster the flux decline with lower mixed foulants retention. It was also revealed that the calcium ions in a basic solution enhanced the combined fouling flux reduction and combined foulants retention. As the major constituent of the combined fouling layer, the adsorption of tannic acid might play a more significant role in the mixed fouling of the FO membrane, which was probably influenced by permeation drag caused by water flux and chemical interactions induced by feed solution pH and calcium ion concentration.

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

    PubMed Central

    Chan, Wing P.; Kung, Fu-Chen; Kuo, Yu-Lin; Yang, Ming-Chen; Lai, Wen-Fu Thomas

    2015-01-01

    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. PMID:26504784

  13. Interaction of metal ions with acid sites of biosorbents peat moss and Vaucheria and model substances alginic and humic acids

    SciTech Connect

    Crist, R.H.; Martin, J.R.; Crist, D.R.

    1999-07-01

    The interaction between added metal ions and acid sites of two biosorbents, peat moss and the alga Vaucheria, was studied. Results were interpreted in terms of two model substances, alginic acid, a copolymer of guluronic and mannuronic acids present in marine algae, and humic acid in peat moss. For peat moss and Vaucheria at pH 4--6, two protons were displaced per Cd sorbed, after correction for sorbed metals also displaced by the heavy metal. The frequent neglect of exchange of heavy metals for metals either sorbed on the native material or added for pH adjustment leads to erroneous conclusions about proton displacement stoichiometry. Proton displacement constants K{sub ex}{sup H} decreased logarithmically with pH and had similar slopes for alginic acid and biosorbents. This pH effect was interpreted as an electrostatic effect of increasing anionic charge making proton removal less favorable. The maximum number of exchangeable acid sites (capacity C{sub H}) decreased with pH for alginic acid but increased with pH for biosorbents. Consistent with titration behavior, this difference was explained in terms of more weak acid sites in the biosorbents.

  14. Effect of dietary alginic acid on juvenile tilapia (Oreochromis niloticus) intestinal microbial balance, intestinal histology and growth performance.

    PubMed

    Merrifield, Daniel L; Harper, Glenn M; Mustafa, Sanaa; Carnevali, Oliana; Picchietti, Simona; Davies, Simon J

    2011-04-01

    The aim of the present study was to assess the effect of a commercial alginic acid source (Ergosan) on tilapia Oreochromis niloticus intestinal microbial balance, intestinal morphology, and growth parameters. Fish were fed a basal control diet or the basal diet plus a source of alginic acid (5 g kg(-1) Ergosan; Schering-Plough Aquaculture, UK) for 9 weeks. At the end of the trial, light and electron microscopy demonstrated that the morphology of the intestinal tract at the gross and ultra-structural level was not affected by dietary alginic acid inclusion. Both groups of fish displayed healthy, normal morphology with no signs of disease, cell or tissue damage. Intestinal epithelial leucocyte infiltration was not affected by dietary alginic acid. Molecular bacterial profiles derived from PCR-DGGE illustrated highly similar microbial communities (both within the lumen and associated with the intestinal mucosa) in the respective treatment groups. Microbial ecological parameters (e.g. species diversity and richness) also remained unaffected. Although not significant, trends towards elevated survival and body protein content were observed in the alginic acid-fed fish. These results are suggestive that alginic acid does not adversely impact the indigenous gastrointestinal microbial balance and subsequently does not impact upon the epithelial brush border integrity. Validation of non-detrimental impacts of immunostimulatory products on gastric microbiota and epithelial integrity should be pursued in future studies as maintaining microbial balance and epithelial integrity is essential for proper gut functionality.

  15. Ca(ii) and Ce(iii) homogeneous alginate hydrogels from the parent alginic acid precursor: a structural study.

    PubMed

    Sonego, Juan Manuel; Santagapita, Patricio R; Perullini, Mercedes; Jobbágy, Matías

    2016-06-14

    Alginate hydrogels are suitable for the encapsulation of biomolecules and microorganisms for the building of bioactive materials. Several alternatives to the conventional alginate formulation are being studied for a broad range of biotechnological applications; among them the crosslinking of alginate by lanthanide cations, Ln(iii), envisages expanded biomedical applications. The performance of these functional materials is highly related to the microstructure of the alginate matrix, which in turn is affected by the conditions of synthesis. In particular, when a diffusing gradient of the crosslinking cation is involved, microstructure inhomogeneities are expected at the macroscopic level. Here we discuss the subtle differences in the microstructure, as assessed by SAXS (Small Angle X-ray Scattering), established in the direction of the gradient of diffusion of Ca(ii) or Ce(iii).

  16. A protein delivery system: biodegradable alginate-chitosan-poly(lactic-co-glycolic acid) composite microspheres.

    PubMed

    Zheng, Cai-Hong; Gao, Jian-Qing; Zhang, Ye-Ping; Liang, Wen-Quan

    2004-10-29

    In the present study we developed alginate-chitosan-poly(lactic-co-glycolic acid) (PLGA) composite microspheres to elevate protein entrapment efficiency and decrease its burst release. Bovine serum albumin (BSA), which used as the model protein, was entrapped into the alginate microcapsules by a modified emulsification method in an isopropyl alcohol-washed way. The rapid drug releases were sustained by chitosan coating. To obtain the desired release properties, the alginate-chitosan microcapsules were further incorporated in the PLGA to form the composite microspheres. The average diameter of the composite microcapsules was 31+/-9microm and the encapsulation efficiency was 81-87%, while that of conventional PLGA microspheres was just 61-65%. Furthermore, the burst releases at 1h of BSA entrapped in composite microspheres which containing PLGA (50:50) and PLGA (70:30) decreased to 24% and 8% in PBS, and further decreased to 5% and 2% in saline. On the contrary, the burst releases of conventional PLGA microspheres were 48% and 52% in PBS, respectively. Moreover, the release profiles could be manipulated by regulating the ratios of poly(lactic acid) to poly(glycolic acid) in the composite microspheres.

  17. [High molecular weight chitosan and sodium alginate effect on secretory acid proteinase of Candida albicans].

    PubMed

    Calamari, Silvia; Bojanich, Alejandra; Barembaum, Silvina; Azcurra, Ana; Virga, Carolina; Dorronsoro, Susana

    2004-12-01

    The effect of high molecular weight chitosan (HMWCh) and sodium alginate (NaAL) on acid proteinase secretion of Candida albicans (one of culture collection and five isolates) was evaluated. The secretion of acid proteinase was induced in the presence and the absence of these polymers in different concentrations and their enzymatic activity was determined. HMWCh and NaAL significantly diminished the enzymatic activity (>76% for the collection strains and > 89% for the isolates, p < 0.05). HMWCh did not modify protein concentrations, but NaAL did. It can be concluded that both polymers can inhibit the proteinase activity of Candida albicans.

  18. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  19. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Potassium alginate...

  20. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium alginate. 184.1724 Section 184.1724 Food and... Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate...

  1. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate is prepared by...

  2. Drug release behavior of poly (lactic-glycolic acid) grafting from sodium alginate (ALG-g-PLGA) prepared by direct polycondensation.

    PubMed

    Shi, Gang; Ding, Yuanyuan; Zhang, Xin; Wu, Luyan; He, Fei; Ni, Caihua

    2015-01-01

    Hydrophobically modified sodium alginate, poly (lactic-glycolic acid) grafting from sodium alginate (ALG-g-PLGA), was successfully synthesized through direct one-step polymerization of sodium alginate, glycolic acid, and lactic acid. ALG-g-PLGA self-assembled to colloidal nanoparticles and subsequently hydrogel microspheres were obtained by crosslinking ALG-g-PLGA nanoparticles in the solution of calcium chloride. The modified hydrogel microspheres could be used as the drug delivery vehicles for a hydrophobic ibuprofen. Compared with sodium alginate, ALG-g-PLGA demonstrated an improved drug loading rate, encapsulation efficiency, and prolonged release speed. The products, as novel and highly promising biomaterials, have potential applications.

  3. Prevention of Polyglycolic Acid-Induced Peritoneal Adhesions Using Alginate in a Rat Model

    PubMed Central

    Matoba, Mari; Hashimoto, Ayumi; Tanzawa, Ayumi; Orikasa, Taichi; Ikeda, Junki; Iwame, Yoshizumi; Ozamoto, Yuki; Miyamoto, Hiroe; Yoshida, Chiko; Hashimoto, Toru; Torii, Hiroko; Takamori, Hideki; Morita, Shinichiro; Tsujimoto, Hiroyuki; Hagiwara, Akeo

    2015-01-01

    Postoperative intra-abdominal or intrathoracic adhesions sometimes cause significant morbidity. We have designed three types of alginate-based treatments using strongly cross-linked (SL), weakly cross-linked (WL), and non-cross-linked (NL) alginate with calcium gluconate. In rat experiments, we compared the antiadhesive effects of the three types of alginate-based treatments, fibrin glue treatment (a standard treatment), and no treatment against adhesions caused by polyglycolic acid (PGA) mesh (PGA-induced adhesions). The antiadhesive materials were set on the PGA sheet fixed on the parietal peritoneum of the abdomen. Fifty-six days later, the adhesions were evaluated macroscopically by the adhesion scores and microscopically by hematoxylin-eosin staining and immunostaining. We also tested the fibroblast growth on the surface of the antiadhesive materials in vitro. The antiadhesive effects of WL and NL were superior to the no treatment and fibrin glue treatment. A microscopic evaluation confirmed that the PGA sheet was covered by a peritoneal layer constructed of well-differentiated mesothelial cells, and the inflammation was most improved in the NL and WL. The fibroblast growth was inhibited most on the surfaces of the NL and WL. These results suggest that either the WL or NL treatments are suitable for preventing PGA-induced adhesions compared to SL or the conventional treatment. PMID:26078949

  4. Energy metabolism and alginate biosynthesis in Pseudomonas aeruginosa: role of the tricarboxylic acid cycle.

    PubMed Central

    Schlictman, D; Kavanaugh-Black, A; Shankar, S; Chakrabarty, A M

    1994-01-01

    Infection with mucoid, alginate-producing strains of Pseudomonas aeruginosa is the leading cause of mortality among patients with cystic fibrosis. Alginate production by P. aeruginosa is not constitutive but is triggered by stresses such as starvation. The algR2 (also termed algQ) gene has been previously identified as being necessary for mucoidy; an algR2 mutant strain is unable to produce alginate when grown at 37 degrees C. We show here that the levels of phosphorylated succinyl coenzyme A synthetase (Scs) and nucleoside diphosphate kinase (Ndk), which form a complex in P. aeruginosa, are reduced in the algR2 mutant. We were able to correlate the lower level of phosphorylated Scs with a decrease in Scs activity. Western blots (immunoblots) also showed a decreased level of Ndk in the algR2 mutant, but the presence of another kinase activity sensitive to Tween 20 provides the missing Ndk function. The effect of AlgR2 on tricarboxylic acid (TCA) cycle enzymes appears to be specific for Scs, since none of the other TCA cycle enzymes measured showed a significant decrease in activity. Furthermore, the ability of the algR2 mutant to grow on TCA cycle intermediates, but not glucose, is impaired. These data indicate that AlgR2 is responsible for maintaining proper operation of the TCA cycle and energy metabolism. Images PMID:7928963

  5. FT-IR spectra of alginic acid block fractions in three species of brown seaweeds.

    PubMed

    Leal, David; Matsuhiro, Betty; Rossi, Miriam; Caruso, Francesco

    2008-02-04

    Sodium alginates obtained by alkaline extraction of Lessonia flavicans, Desmarestia ligulata and Desmarestia distans (Phaeophyta) from southern Chile were partially hydrolyzed with HCl. Each alginate gave three fractions that were characterized using FT-IR spectroscopy. The fractions soluble in 0.3M HCl presented in the fingerprint region four vibrations at around 960, 911, 890 and 815 cm(-1) that were assigned to heteropolymeric blocks. The fractions soluble at pH 2.85 showed bands at around 948, 888 and 820 cm(-1) attributed to homopolymannuronic acid blocks, the first band is resolved in the second-derivative spectra into two bands at 951 and 936 cm(-1). The fractions insoluble at pH 2.85 presented four bands at around 947, 903, 812 and 781 cm(-1), which were assigned to homopolyguluronic acid blocks. For some samples, the second derivative FT-IR spectra showed new bands indicating the presence of other structures, in low proportions. Structures deduced by FT-IR spectroscopy were corroborated by solution (1)H and (13)C NMR spectroscopy. Two-dimensional spectra were collected to confirm the fine structure of the hetero- and homopolymeric fractions. A geometrically optimized model for the disaccharide alpha-l-gulopyranuronosyl-(1-->4)-alpha-l-gulopyranuronic acid was calculated using density functional theory; good agreement was obtained between its corresponding calculated vibrations and the experimental bands assigned to homopolyguluronic acid blocks.

  6. Novel one-pot synthesis of dicarboxylic acids mediated alginate-zirconium biopolymeric complex for defluoridation of water.

    PubMed

    Prabhu, Subbaiah Muthu; Meenakshi, Sankaran

    2015-04-20

    The present investigation explains the fluoride removal from aqueous solution using alginate-zirconium complex prepared with respective dicarboxylic acids like oxalic acid (Ox), malonic acid (MA) and succinic acid (SA) as a medium. The complexes viz., alginate-oxalic acid-zirconium (Alg-Ox-Zr), alginate-malonic acid-zirconium (Alg-MA-Zr) and alginate-succinic acid-zirconium (Alg-SA-Zr) were synthesized and studied for fluoride removal. The synthesized complexes were characterized by FTIR, XRD, SEM with EDAX and mapping images. The effects of various operating parameters were optimized. The result showed that the maximum removal of fluoride 9653mgF(-)/kg was achieved by Alg-Ox-Zr complex at acidic pH in an ambient atmospheric condition. Equilibrium data of Alg-Ox-Zr complex was fitted well with Freundlich isotherm. The calculated values of thermodynamic parameters indicated that the fluoride adsorption is spontaneous and endothermic in nature. The mechanism of fluoride removal behind Alg-Ox-Zr complex has been proposed in detail. The suitability of the Alg-Ox-Zr complex has been tested with the field sample collected in a nearby fluoride endemic area.

  7. Neuralization of mouse embryonic stem cells in alginate hydrogels under retinoic acid and SAG treatment.

    PubMed

    Delivopoulos, Evangelos; Shakesheff, Kevin M; Peto, Heather

    2015-08-01

    This paper examines the differentiation of a mouse embryonic stem cell line (CGR8) into neurons, under retinoic acid (RA) and smoothened agonist (SAG) treatment. When stem cells underwent through an embryoid body (EB) formation stage, dissociation and seeding on glass coverslips, immunofluorescent labelling for neuronal markers (Nestin, b-Tubulin III, MAP2) revealed the presence of both immature neural progenitors and mature neurons. Undifferentiated CGR8 were also encapsulated in tubular, alginate-gelatin hydrogels and incubated in differentiation media containing retinoic acid (RA) and smoothened agonist (SAG). Cryo-sections of the hydrogel tubes were positive for Nestin, Pax6 and b-Tubulin III, verifying the presence of neurons and neural progenitors. Provided neural induction can be more precisely directed in the tubular hydrogels, these scaffolds will become a powerful model of neural tube development in embryos and will highlight potential strategies for spinal cord regeneration.

  8. An acid/alkaline stress and the addition of amino acids induce a prolonged viability of Lactobacillus plantarum loaded into alginate gel.

    PubMed

    Bevilacqua, Antonio; Sinigaglia, Milena; Corbo, Maria Rosaria

    2010-08-15

    This study reports on the investigation on the effects of the conditions used throughout the step of biomass production on the survival of Lactobacillus plantarum loaded into alginate gels. L. plantarum was grown under different conditions (MRS or a laboratory medium-LB(2)-at acidic or alkaline pHs, with NaCl, phenols, vitamins or amino acids) and immobilized in sodium alginate; cell number was evaluated throughout the storage and death (delta(stand)) and first-reduction times (delta) were calculated. The storage of alginate gels at 4 degrees C prolonged cell viability up to 60 days (ca. 20 days for cells produced in MRS and stored at 30 degrees C); however, a similar prolongation was achieved for cells produced in LB(2) adjusted to pH 5.0 and 9.0 or added with amino acids (death time>50-60 days).

  9. Lactic acid fermentation by cells immobilised on various porous cellulosic materials and their alginate/poly-lactic acid composites.

    PubMed

    Kumar, Mrinal Nishant; Gialleli, Angelika-Ioanna; Masson, Jean Bernard; Kandylis, Panagiotis; Bekatorou, Argyro; Koutinas, Athanasios A; Kanellaki, Maria

    2014-08-01

    Porous delignified cellulose (or tubular cellulose, abbr. TC) from Indian Mango (Mangifera indica) and Sal (Shorea robusta) wood and Rice husk, and TC/Ca-alginate/polylactic acid composites, were used as Lactobacillus bulgaricus immobilisation carriers leading to improvements in lactic acid fermentation of cheese whey and synthetic lactose media, compared to free cells. Specifically, shorter fermentation rates, higher lactic acid yields (g/g sugar utilised) and productivities (g/Ld), and higher amounts of volatile by-products were achieved, while no significant differences were observed on the performance of the different immobilised biocatalysts. The proposed biocatalysts are of food grade purity, cheap and easy to prepare, and they are attractive for bioprocess development based on immobilised cells. Such composite biocatalysts may be used for the co-immobilisation of different microorganisms or enzymes (in separate layers of the biocatalyst), to efficiently conduct different types of fermentations in the same bioreactor, avoiding inhibition problems of chemical or biological (competition) nature.

  10. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  11. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  12. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  13. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  14. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  15. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  16. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  17. Understanding Alginate Gel Development for Bioclogging and Biogeophysical Experiments

    NASA Astrophysics Data System (ADS)

    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

  18. Biomedical-grade, high mannuronic acid content (BioMVM) alginate enhances the proteoglycan production of primary human meniscal fibrochondrocytes in a 3-D microenvironment

    PubMed Central

    Rey-Rico, Ana; Klich, Angelique; Cucchiarini, Magali; Madry, Henning

    2016-01-01

    Alginates are important hydrogels for meniscus tissue engineering as they support the meniscal fibrochondrocyte phenotype and proteoglycan production, the extracellular matrix (ECM) component chiefly responsible for its viscoelastic properties. Here, we systematically evaluated four biomedical- and two nonbiomedical-grade alginates for their capacity to provide the best three-dimensional (3-D) microenvironment and to support proteoglycan synthesis of encapsulated human meniscal fibrochondrocytes in vitro. Biomedical-grade, high mannuronic acid alginate spheres (BioLVM, BioMVM) were the most uniform in size, indicating an effect of the purity of alginate on the shape of the spheres. Interestingly, the purity of alginates did not affect cell viability. Of note, only fibrochondrocytes encapsulated in BioMVM alginate produced and retained significant amounts of proteoglycans. Following transplantation in an explant culture model, the alginate spheres containing fibrochondrocytes remained in close proximity with the meniscal tissue adjacent to the defect. The results reveal a promising role of BioMVM alginate to enhance the proteoglycan production of primary human meniscal fibrochondrocytes in a 3-D hydrogel microenvironment. These findings have significant implications for cell-based translational studies aiming at restoring lost meniscal tissue in regions containing high amounts of proteoglycans. PMID:27302206

  19. Synthesis and characterisation of multifunctional alginate microspheres via the in situ formation of ZnO quantum dots and the graft of 4-(1-pyrenyl) butyric acid to sodium alginate.

    PubMed

    Luo, Guilin; Wang, Jianxin; Wang, Yingying; Feng, Bo; Weng, Jie

    2015-01-01

    Growth factor-loaded fluorescent alginate microspheres, which can realise sustained growth factor release and fluorescence imaging, were synthesised by in situ formation of ZnO quantum dots (QDs) and covalent graft of 4-(1-pyrenyl) butyric acid (PBA). BSA was chosen as a growth factor model protein to study the release kinetic of growth factors from alginate microspheres. The microsphere size and fluorescent properties were also investigated. Investigations of cell culture were used for evaluating biocompatibility of BSA-loaded fluorescent microspheres and fluorescence imaging property of ZnO QDs and PBA-grafted sodium alginate from the microspheres. The results show that they have good fluorescent property either to microspheres or to cells and fluorescent microspheres have good biocompatibility and property in sustained release of growth factors. The obtained microspheres will be expected to realise the imaging of cells and materials and also the release of growth factor in tissue engineering or in cell culture.

  20. PEI-alginate nanocomposites: efficient non-viral vectors for nucleic acids.

    PubMed

    Patnaik, Soma; Arif, Mohammed; Pathak, Atul; Singh, Naresh; Gupta, K C

    2010-01-29

    Branched polyethylenimine (PEI, 25 kDa) was ionically interacted with varying amount of alginic acid to block different proportion (2.6-5.7%) of amines in PEI to form a series of nanocomposites, PEI-Al. These nanocomposites, upon interaction with DNA, protected it against DNase I. Among various complexes evaluated, PEI-Al(4.8%)/DNA displayed the highest transfection efficiency in HEK293, COS-1 and HeLa cells that was approximately 2-8-folds higher than Superfect, Fugene, PEI (750 kDa)-Al(6.26%) and PEI alone. The projected nanocomposites were nearly non-toxic to cells in vitro. Furthermore, the concentration of PEI-Al(4.8%) needed to deliver GFP-specific siRNA in COS-1 cells was 20 times lower than PEI (750 kDa)-Al(6.26%). Intracellular trafficking of PEI-Al(4.8%) with or without complexed DNA in HeLa cells shows that both appear in the nucleus after 1 h.

  1. Boron removal by a composite sorbent: Polyethylenimine/tannic acid derivative immobilized in alginate hydrogel beads.

    PubMed

    Bertagnolli, Caroline; Grishin, Andrey; Vincent, Thierry; Guibal, Eric

    2017-03-21

    A novel composite material was prepared by the grafting of tannic acid on polyethylenimine (PEI), which allows an efficient sorption of boron (sorption capacity close to 0.89 mmol B g(-1)). The encapsulation of this chelating sorbent (finely crushed) facilitates its use (readily solid/liquid separation, use in fixed-bed columns) at the expense of a loss in sorption capacity (proportionally decreased by the introduction of alginate having poor efficiency for boron uptake). Sorption isotherms are modeled using the Langmuir equation, while the kinetic profiles are presented a good fit by pseudo-second order rate equation. In addition, the encapsulating matrix introduces supplementary resistance to intraparticle diffusion, especially when the resin is dried without control: freeze-drying partially limits this effect. The stability (at long-term storage) of the sorbent is improved when the sorbent is stored under nitrogen atmosphere. The presence of an excess of NaCl was investigated. The degradation of the hydrogel (by ion-exchange of Ca(II) with Na(I)) leads to a decrease in the sorption performance of composite material but the action of Ca(II) ions in the solutions re-stabilizes the hydrogel.

  2. Preparation and li storage properties of hierarchical porous carbon fibers derived from alginic acid.

    PubMed

    Wu, Xing-Long; Chen, Li-Li; Xin, Sen; Yin, Ya-Xia; Guo, Yu-Guo; Kong, Qing-Shan; Xia, Yan-Zhi

    2010-06-21

    One-dimensional (1D) hierarchical porous carbon fibers (HPCFs) have been prepared by controlled carbonization of alginic acid fibers and investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, nitrogen adsorption-desorption isotherms, and electrochemical tests toward lithium storage. The as-obtained HPCFs consist of a 3D network of nanosized carbon particles with diameters less than 10 nm and exhibit a hierarchical porous architecture composed of both micropores and mesopores. Electrochemical measurements show that HPCFs exhibit excellent rate capability and capacity retention compared with commercial graphite when employed as anode materials for lithium-ion batteries. At the discharge/charge rate of 45 C, the reversible capacity of HPCFs is still as high as 80 mA h g(-1) even after 1500 cycles, which is about five times larger than that of commercial graphite anode. The much improved electrochemical performances could be attributed to the nanosized building blocks, the hierarchical porous structure, and the 1D morphology of HPCFs.

  3. A bio-injectable algin-aminocaproic acid thixogel with tri-stimuli responsiveness.

    PubMed

    Chejara, Dharmesh R; Mabrouk, Mostafa; Badhe, Ravindra V; Mulla, Jameel A S; Kumar, Pradeep; Choonara, Yahya E; du Toit, Lisa C; Pillay, Viness

    2016-01-01

    In this article a novel bio-injectable algin-aminocaproic acid (Alg-ACA) tri-stimuli responsive thixogel system is reported. The designed soft thixotrophic hydrogel (thixogel) was characterized using various analytical techniques such as FT-IR, NMR, SEM, AFM and DSC. The soft thixogel system was further investigated for stress responsiveness using different rheological studies which confirmed the thixotropic nature of the gel [Thixotropic area (Ar) of Alg-ACA (1:0.5), Alg-ACA (1:1) and Alg-ACA (1:2), were 23.5%, 43.1%, and 27.59%, respectively, which were higher than that of Na-Alg (2.08%)]. The thixogel also demonstrated temperature and ultrasonication responsiveness. This tri-stimuli responsive soft thixogel system was rendered flowable (fluid) on applying the described physical stimuli and recovered its "rigid" gel structure upon removal of the applied stimuli. This approach of synthesizing a thixogels may be applicable to a broad variety of other natural polymers and has the potential for use in biomedical applications.

  4. Pervaporation dehydration of ethanol by hyaluronic acid/sodium alginate two-active-layer composite membranes.

    PubMed

    Gao, Chengyun; Zhang, Minhua; Ding, Jianwu; Pan, Fusheng; Jiang, Zhongyi; Li, Yifan; Zhao, Jing

    2014-01-01

    The composite membranes with two-active-layer (a capping layer and an inner layer) were prepared by sequential spin-coatings of hyaluronic acid (HA) and sodium alginate (NaAlg) on the polyacrylonitrile (PAN) support layer. The SEM showed a mutilayer structure and a distinct interface between the HA layer and the NaAlg layer. The coating sequence of two-active-layer had an obvious influence on the pervaporation dehydration performance of membranes. When the operation temperature was 80 °C and water concentration in feed was 10 wt.%, the permeate fluxes of HA/Alg/PAN membrane and Alg/HA/PAN membrane were similar, whereas the separation factor were 1130 and 527, respectively. It was found that the capping layer with higher hydrophilicity and water retention capacity, and the inner layer with higher permselectivity could increase the separation performance of the composite membranes. Meanwhile, effects of operation temperature and water concentration in feed on pervaporation performance as well as membrane properties were studied.

  5. Synthesis of zinc-crosslinked thiolated alginic acid beads and their in vitro evaluation as potential enteric delivery system with folic acid as model drug.

    PubMed

    Taha, M O; Aiedeh, K M; Al-Hiari, Y; Al-Khatib, H

    2005-10-01

    The aim of this study is to explore the potential of synthetic modifications of alginic acid as a method to enhance the stability of its complexes with divalent cations under physiological conditions. A fraction of algin's carboxylic acid moieties was substituted with thiol groups to different substitution degrees through conjugating alginate to cysteine to produce alginate-cysteine (AC) conjugates. Infrared spectrophotometry and iodometry were used to characterize the resulting polymeric conjugates in terms of structure and degree of substitution. Moreover, zinc ions were used to crosslink the resulting AC polymers. Folic acid loaded beads were prepared from Zinc-crosslinked AC polymers (AC-Zn) of different cysteine substitution degrees. The generated beads were then investigated in vitro for their capacity to modify folic acid release. AC-Zn polymeric beads resisted drug release under acidic conditions (pH 1.0). However, upon transfer to a phosphate buffer solution (pH 7.0) they released most of their contents almost immediately. This change in drug release behavior is most probably due to the sequestering of zinc cations by phosphate ions within the buffer solution to form insoluble chelates and, to a lesser extent, the ionization of the carboxylic acid and thiol moieties. Removal of zinc ions from the polymeric matrix seems to promote polymeric disintegration and subsequent drug release. A similar behavior is expected in vivo due to the presence of natural zinc sequestering agents in the intestinal fluids. AC-Zn polymers provided a novel approach for enteric drug delivery as drug release from these matrices complied with the USP specifications for enteric dosage forms.

  6. The Effect of Chondroitin Sulphate and Hyaluronic Acid on Chondrocytes Cultured within a Fibrin-Alginate Hydrogel.

    PubMed

    Little, Christopher J; Kulyk, William M; Chen, Xiongbiao

    2014-09-18

    Osteoarthritis is a painful degenerative joint disease that could be better managed if tissue engineers can develop methods to create long-term engineered articular cartilage tissue substitutes. Many of the tissue engineered cartilage constructs currently available lack the chemical stimuli and cell-friendly environment that promote the matrix accumulation and cell proliferation needed for use in joint cartilage repair. The goal of this research was to test the efficacy of using a fibrin-alginate hydrogel containing hyaluronic acid (HA) and/or chondroitin sulphate (CS) supplements for chondrocyte culture. Neonatal porcine chondrocytes cultured in fibrin-alginate hydrogels retained their phenotype better than chondrocytes cultured in monolayer, as evidenced by analysis of their relative expression of type II versus type I collagen mRNA transcripts. HA or CS supplementation of the hydrogels increased matrix glycosaminoglycan (GAG) production during the first week of culture. However, the effects of these supplements on matrix accumulation were not additive and were no longer observed after two weeks of culture. Supplementation of the hydrogels with CS or a combination of both CS and HA increased the chondrocyte cell population after two weeks of culture. Statistical analysis indicated that the HA and CS treatment effects on chondrocyte numbers may be additive. This research suggests that supplementation with CS and/or HA has positive effects on cartilage matrix production and chondrocyte proliferation in three-dimensional (3D) fibrin-alginate hydrogels.

  7. Alginic acid-based macromolecular chemiluminescent probe for universal protein assay on a solid-phase membrane.

    PubMed

    Krawczyk, Tomasz; Kondo, Midori; Azam, Md Golam; Zhang, Huan; Shibata, Takayuki; Kai, Masaaki

    2010-11-01

    A novel chemiluminescent (CL) technique for the rapid determination of proteins on a membrane is described. The method utilizes an interaction between luminol-labeled alginic acid macromolecule and proteins. The synthesis of the macromolecular probe consists of the oxidation of alginic acid with NaIO(4), the introduction of luminol through imine formation as a CL tag, and the reduction of the conjugate with NaBH(4) to obtain the stable probe. The analytical protocol consists of adsorbing proteins on a poly(vinylidene difluoride) (PVDF) membrane, incubating the membrane for 30 min with the probe solution in the presence of boric acid and a surfactant, two short washing steps in order to remove an excess of the probe, and detection of CL intensity with hemin, tetra-n-propylammonium hydroxide and H(2)O(2). This proposed CL assay for proteins can be finished within 1 h, and indicates the detection limit of 15-250 ng of proteins on the membrane. The CL signals in the calibration curves for some proteins such as albumin show proportional intensities against the amounts of the proteins less than ca. 125 ng, though there is a logarithmic relationship between the CL signals and the protein amounts larger than ca. 125 ng. However, some other proteins indicate the proportional CL intensities against the increasing amounts in wider range up to 500 ng of the proteins. The synthesised alginic acid-based probe indicates specific selectivity towards proteins, and should be used as a CL probe for the universal detection of various proteins on a solid-phase membrane even in the presence of DNA and RNA.

  8. Lipase in biphasic alginate beads as a biocatalyst for esterification of butyric acid and butanol in aqueous media.

    PubMed

    Ng, Choong Hey; Yang, Kun-Lin

    2016-01-01

    Esterification of organic acids and alcohols in aqueous media is very inefficient due to thermodynamic constraints. However, fermentation processes used to produce organic acids and alcohols are often conducted in aqueous media. To produce esters in aqueous media, biphasic alginate beads with immobilized lipase are developed for in situ esterification of butanol and butyric acid. The biphasic beads contain a solid matrix of calcium alginate and hexadecane together with 5 mg/mL of lipase as the biocatalyst. Hexadecane in the biphasic beads serves as an organic phase to facilitate the esterification reaction. Under optimized conditions, the beads are able to catalyze the production of 0.16 mmol of butyl butyrate from 0.5 mmol of butyric acid and 1.5 mmol of butanol. In contrast, when monophasic beads (without hexadecane) are used, only trace amount of butyl butyrate is produced. One main application of biphasic beads is in simultaneous fermentation and esterification (SFE) because the organic phase inside the beads is very stable and does not leach out into the culture medium. SFE is successfully conducted with an esterification yield of 6.32% using biphasic beads containing iso-octane even though the solvent is proven toxic to the butanol-producing Clostridium spp.

  9. The influence of polymeric component of bioactive glass-based nanocomposite paste on its rheological behaviors and in vitro responses: hyaluronic acid versus sodium alginate.

    PubMed

    Sohrabi, Mehri; Hesaraki, Saeed; Kazemzadeh, Asghar

    2014-04-01

    Different biocomposite pastes were prepared from a solid phase that was nanoparticles of sol-gel-derived bioactive glass and different liquid phases including 3% hyaluronic acid solution, sodium alginate solutions (3% and 10 %) or mixtures of hyaluronic acid and sodium alginate (3% or 10 %) solutions in 50:50 volume ratio. Rheological properties of the pastes were measured in both rotatory and oscillatory modes. The washout behavior and in vitro apatite formation of the pastes were determined by soaking them in simulated body fluid under dynamic situation for 14 days. The proliferation and alkaline phosphatase activity of MG-63 osteoblastic cells were also determined using extracts of the pastes. All pastes could be easily injected from the standard syringes with different tip diameters. All pastes exhibited visco-elastic character, but a nonthixotropic paste was obtained using hyaluronic acid in which the loss modulus was higher than the storage modulus. The thixotropy and storage modulus were increasingly improved by adding/using sodium alginate as mixing liquid. Moreover, the pastes in which the liquid phase was sodium alginate or mixture of hyaluronic acid and 10% sodium alginate solution revealed better apatite formation ability and washout resistance than that made of hyaluronic acid alone. No cytotoxicity effects were observed by extracts of the pastes on osteoblasts but better alkaline phosphatase activity was found for the pastes containing hyaluronic acid. Overall, injectable biocomposites can be produced by mixing bioactive glass nanoparticles and sodium alginate/hyaluronic acid polymers. They are potentially useful for hard and even soft tissues treatments.

  10. Characterization of the radical-scavenging reaction of 2-O-substituted ascorbic acid derivatives, AA-2G, AA-2P, and AA-2S: a kinetic and stoichiometric study.

    PubMed

    Takebayashi, Jun; Tai, Akihiro; Gohda, Eiichi; Yamamoto, Itaru

    2006-04-01

    The aim of this study was to characterize the antioxidant activity of three ascorbic acid (AA) derivatives O-substituted at the C-2 position of AA: ascorbic acid 2-glucoside (AA-2G), ascorbic acid 2-phosphate (AA-2P), and ascorbic acid 2-sulfate (AA-2S). The radical-scavenging activities of these AA derivatives and some common low molecular-weight antioxidants such as uric acid or glutathione against 1,1-diphenyl-picrylhydrazyl (DPPH) radical, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS+), or galvinoxyl radical were kinetically and stoichiometrically evaluated under pH-controlled conditions. Those AA derivatives slowly and continuously reacted with DPPH radical and ABTS+, but not with galvinoxyl radical. They effectively reacted with DPPH radical under acidic conditions and with ABTS+ under neutral conditions. In contrast, AA immediately quenched all species of radicals tested at all pH values investigated. The reactivity of Trolox, a water-soluble vitamin E analogue, was comparable to that of AA in terms of kinetics and stoichiometrics. Uric acid and glutathione exhibited long-lasting radical-scavenging activity against these radicals under certain pH conditions. The radical-scavenging profiles of AA derivatives were closer to those of uric acid and glutathione rather than to that of AA. The number of radicals scavenged by one molecule of AA derivatives, uric acid, or glutathione was equal to or greater than that by AA or Trolox under the appropriate conditions. These data suggest the potential usage of AA derivatives as radical scavengers.

  11. The amino acid sequence of protein AA from a burro (Equus asinus).

    PubMed

    Sletten, Knut; Johnson, Kenneth H; Westermark, Per

    2003-09-01

    The primary structure of amyloid fibril protein AA of a burro has been determined by Edman degradation. The 80 amino acid residue long protein shows strong resemblance to that of other mammalian AA-proteins and differs from equine protein AA at 5 positions: Burro/horse positions 20 (Q/N), 44 (R,Q, K/K,Q), 59 (G,L/G,A), 61 (Q/E) and 65 (N/R).

  12. TiO2 nanoparticles aggregation and disaggregation in presence of alginate and Suwannee River humic acids. pH and concentration effects on nanoparticle stability.

    PubMed

    Loosli, Frédéric; Le Coustumer, Philippe; Stoll, Serge

    2013-10-15

    The behavior of manufactured TiO2 nanoparticles is studied in a systematic way in presence of alginate and Suwannee River humic acids at variable concentrations. TiO2 nanoparticles aggregation, disaggregation and stabilization are investigated using dynamic light scattering and electrophoretic experiments allowing the measurement of z-average hydrodynamic diameters and zeta potential values. Stability of the TiO2 nanoparticles is discussed by considering three pH-dependent electrostatic scenarios. In the first scenario, when pH is below the TiO2 nanoparticle point of zero charge, nanoparticles exhibit a positively charged surface whereas alginate and Suwannee River humic acids are negatively charged. Fast adsorption at the TiO2 nanoparticles occurs, promotes surface charge neutralization and aggregation. By increasing further alginate and Suwannee River humic acids concentrations charge inversion and stabilization of TiO2 nanoparticles are obtained. In the second electrostatic scenario, at the surface charge neutralization pH, TiO2 nanoparticles are rapidly forming aggregates. Adsorption of alginate and Suwannee River humic acids on aggregates leads to their partial fragmentation. In the third electrostatic scenario, when nanoparticles, alginate and Suwannee River humic acids are negatively charged, only a small amount of Suwannee River humic acids is adsorbed on TiO2 nanoparticles surface. It is found that the fate and behavior of individual and aggregated TiO2 nanoparticles in presence of environmental compounds are mainly driven by the complex interplay between electrostatic attractive and repulsive interactions, steric and van der Waals interactions, as well as concentration ratio. Results also suggest that environmental aquatic concentration ranges of humic acids and biopolymers largely modify the stability of aggregated or dispersed TiO2 nanoparticles.

  13. Adipic acid dihydrazide treated partially oxidized alginate beads for sustained oral delivery of flurbiprofen.

    PubMed

    Maiti, Sabyasachi; Singha, Kamalika; Ray, Somasree; Dey, Paramita; Sa, Biswanath

    2009-01-01

    In this study, periodate oxidation of sodium alginate was controlled such that the oxidized alginate could form isolatable beads with Ca(+2) ions. The beads of oxidized alginate having a degree of oxidation 1 mol%, entrapped 89% flurbiprofen and released almost all of its content within 1.5 h in pH 7.2 phosphate buffer solution. The beads were covalently crosslinked with adipic dihydrazide (ADH) in addition to ionic crosslinks and were characterized. Scanning electron microscopy revealed that the beads were spherical having smooth surfaces. The drug entrapment efficiency decreased (90-86%) with increasing concentration of ADH (2-6% w/v) in the gelation medium. However, the beads prolonged the drug release in alkaline dissolution medium up to 8 h depending upon the concentration of ADH. The beads prepared with 2% ADH swelled more rapidly and led to faster drug release in either pH 1.2 HCl solution or pH 7.2 phosphate buffer solution. The swelling tendencies were reduced and the drug release became slower with higher concentrations in either fluid. The drug diffusion from the beads followed super case II transport mechanism. FTIR spectroscopy indicated stable nature of flurbiprofen in the beads and therefore had potential as sustained oral delivery system for the drug.

  14. Alginate Production by Plant-Pathogenic Pseudomonads

    PubMed Central

    Fett, William F.; Osman, Stanley F.; Fishman, Marshall L.; Siebles, T. S.

    1986-01-01

    Eighteen plant-pathogenic and three non-plant-pathogenic pseudomonads were tested for the ability to produce alginic acid as an exopolysaccharide in vitro. Alginate production was demonstrated for 10 of 13 fluorescent plant-pathogenic pseudomonads tested with glucose or gluconate as the carbon source, but not for all 5 nonfluorescent plant pathogens and all 3 non-plant pathogens tested. With sucrose as the carbon source, some strains produced alginate while others produced both polyfructan (levan) and alginate. Alginates ranged from <1 to 28% guluronic acid, were acetylated, and had number-average molecular weights of 11.3 × 103 to 47.1 × 103. Polyfructans and alginates were not elicitors of the soybean phytoalexin glyceollin when applied to wounded cotyledon surfaces and did not induce prolonged water soaking of soybean leaf tissues. All or most pseudomonads in rRNA-DNA homology group I may be capable of synthesizing alginate as an exopolysaccharide. PMID:16347146

  15. Effect of rate of pyrolysis on the textural properties of naturally-templated porous carbons from alginic acid.

    PubMed

    Marriott, Andrew S; Hunt, Andrew J; Bergström, Ed; Thomas-Oates, Jane; Clark, James H

    2016-09-01

    The effect of pyrolysis rate on the properties of alginic acid-derived carbonaceous materials, termed Starbon(®), was investigated. Thermal Gravimetry-IR was used to prepare porous carbons up to 800 °C at several rates and highlighted increased CO2 production at higher pyrolysis rates. N2 porosimetry of the resultant carbons shows how pyrolysis rate affects both the mesopore structure and thus surface area and surface energy. Surface capacity of these carbons was analysed by methylene blue dye adsorption. In general, as the rate of pyrolysis increased, the mesopore content and adsorbent capacity decreased. It is considered here that the rapid production of volatiles at these higher rates causes structural collapse of the non-templated pore network. The work here demonstrates that pyrolysis rate is a key variable which needs to be controlled to maximise the textural properties of Starbon(®) required for adsorption applications.

  16. Alginate-modifying enzymes: biological roles and biotechnological uses

    PubMed Central

    Ertesvåg, Helga

    2015-01-01

    Alginate denotes a group of industrially important 1-4-linked biopolymers composed of the C-5-epimers β-D-mannuronic acid (M) and α-L-guluronic acid (G). The polysaccharide is manufactured from brown algae where it constitutes the main structural cell wall polymer. The physical properties of a given alginate molecule, e.g., gel-strength, water-binding capacity, viscosity and biocompatibility, are determined by polymer length, the relative amount and distribution of G residues and the acetyl content, all of which are controlled by alginate modifying enzymes. Alginate has also been isolated from some bacteria belonging to the genera Pseudomonas and Azotobacter, and bacterially synthesized alginate may be O-acetylated at O-2 and/or O-3. Initially, alginate is synthesized as polymannuronic acid, and some M residues are subsequently epimerized to G residues. In bacteria a mannuronan C-5-epimerase (AlgG) and an alginate acetylase (AlgX) are integral parts of the protein complex necessary for alginate polymerization and export. All alginate-producing bacteria use periplasmic alginate lyases to remove alginate molecules aberrantly released to the periplasm. Alginate lyases are also produced by organisms that utilize alginate as carbon source. Most alginate-producing organisms encode more than one mannuronan C-5 epimerase, each introducing its specific pattern of G residues. Acetylation protects against further epimerization and from most alginate lyases. An enzyme from Pseudomonas syringae with alginate deacetylase activity has been reported. Functional and structural studies reveal that alginate lyases and epimerases have related enzyme mechanisms and catalytic sites. Alginate lyases are now utilized as tools for alginate characterization. Secreted epimerases have been shown to function well in vitro, and have been engineered further in order to obtain enzymes that can provide alginates with new and desired properties for use in medical and pharmaceutical applications

  17. Targeted removal of trichlorophenol in water by oleic acid-coated nanoscale palladium/zero-valent iron alginate beads.

    PubMed

    Chang, Jaewon; Woo, Heesoo; Ko, Myoung-Soo; Lee, Jaesang; Lee, Seockheon; Yun, Seong-Taek; Lee, Seunghak

    2015-08-15

    A new material was developed and evaluated for the targeted removal of trichlorophenol (TCP) from among potential interferents which are known to degrade removal activity. To achieve TCP-targeted activity, an alginate bead containing nanoscale palladium/zero-valent iron (Pd/nZVI) was coated with a highly hydrophobic oleic acid layer. The new material (Pd/nZVI-A-O) preferentially sorbed TCP from a mixture of chlorinated phenols into the oleic acid cover layer and subsequently dechlorinated it to phenol. The removal efficacy of TCP by Pd/nZVI-A-O was not affected by co-existing organic substances such as Suwannee River humic acid (SRHA), whereas the material without the oleic acid layer (Pd/nZVI-A) became less effective with increasing SRHA concentration. The inorganic substances nitrate and phosphate significantly reduced the reactivity of Pd/nZVI-A, however, Pd/nZVI-A-O showed similar TCP removal efficacies regardless of the initial inorganic ion concentrations. The influence of bicarbonate on the TCP removal efficacies of both Pd/nZVI-A and Pd/nZVI-A-O was not significant. The findings from this study suggest that Pd/nZVI-A-O, with its targeted, constant reactivity for TCP, would be effective for treating this contaminant in surface water or groundwater containing various competitive substrates.

  18. Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

    2015-11-01

    Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

  19. Enhanced drug encapsulation and extended release profiles of calcium-alginate nanoparticles by using tannic acid as a bridging cross-linking agent.

    PubMed

    Abulateefeh, Samer R; Taha, Mutasem O

    2015-01-01

    Calcium alginate nanoparticles (NPs) suffer from sub-optimal stability in bio-relevant media leading to low drug encapsulation efficiency and uncontrolled release profiles. To sort out these drawbacks, a novel approach is proposed herein based on introducing tannic acid into these NPs to act as a bridging cross-linking aid agent. Calcium-alginate NPs were prepared by the ionotropic gelation method and loaded with diltiazem hydrochloride as a model drug. These NPs were characterized in terms of particle size, zeta potential, and morphology, and results were explained in accordance with Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The incorporation of tannic acid led to more than four folds increase in drug encapsulation efficiency (i.e. from 15.3% to 69.5%) and reduced burst drug release from 44% to around 10% within the first 30 min. These findings suggest the possibility of improving the properties of Ca-alginate NPs by incorporating cross-linking aid agents under mild conditions.

  20. Relevance of charge balance and hyaluronic acid on alginate-chitosan sponge microstructure and its influence on fibroblast growth.

    PubMed

    Orellana, Sandra L; Giacaman, Annesi; Pavicic, Francisca; Vidal, Alejandra; Moreno-Villoslada, Ignacio; Concha, Miguel

    2016-10-01

    The study of biomaterials by electrical charge scaling to explore the role of net charge on biocompatibility and suitability for tissue regeneration has been limited as has the search for products that could improve this first-rate variable. In the present study, we prepared sponges composed of chitosan/alginate (CS/ALG) with or without hyaluronic acid (HA) by mixing polymer stock solutions of different net electric charge ratios (n(+/) n(-) ), and then lyophilizing them to obtain porous materials. The electric charge ratios n(+/) n(-) studied were 0.3, 0.8, 1.0, and 2.5 for CS/ALG and 0.3, 1.0, 1.9, and 3.7 for CS/ALG/HA sponges. Under these conditions a role for net electric charge balance over sponge microstructure rearrangement, protection to dissolution, cellular proliferation, and cell-cell interactions was apparent, effects that were enhanced by copolymer modification with HA. Mass balance, electric charge, and specific products that influence both such as HA, have a potential in biomaterials for wound healing. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2537-2543, 2016.

  1. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... alginic acid, a natural polyuronide constituent of certain brown algae. Calcium alginate is prepared by... Do. Fats and oils, § 170.3(n)(12) of this chapter 0.5 Do. Gelatins, puddings, § 170.3(n)(22) of...

  2. Oxidation of alginate and pectate biopolymers by cerium(IV) in perchloric and sulfuric acid solutions: A comparative kinetic and mechanistic study.

    PubMed

    Fawzy, Ahmed

    2016-03-15

    The kinetics of oxidation of alginate (Alg) and pectate (Pec) carbohydrate biopolymers was studied by spectrophotometry in aqueous perchloric and sulfuric acid solutions at fixed ionic strengths and temperature. In both acids, the reactions showed a first order dependence on [Ce(IV)], whereas the orders with respect to biopolymer concentrations are less than unity. In perchloric acid, the reactions exhibited less than unit orders with respect to [H(+)] whereas those proceeded in sulfuric acid showed negative fractional-first order dependences on [H(+)]. The effect of ionic strength and dielectric constant was studied. Probable mechanistic schemes for oxidation reactions were proposed. In both acids, the final oxidation products were characterized as mono-keto derivatives of both biopolymers. The activation parameters with respect to the slow step of the mechanisms were computed and discussed. The rate laws were derived and the reaction constants involved in the different steps of the mechanisms were calculated.

  3. AA-PMe, a novel asiatic acid derivative, induces apoptosis and suppresses proliferation, migration, and invasion of gastric cancer cells.

    PubMed

    Jing, Yue; Wang, Gang; Ge, Ying; Xu, Minjie; Tang, Shuainan; Gong, Zhunan

    2016-01-01

    Asiatic acid (AA; 2α,3β,23-trihydroxyurs-12-ene-28-oic acid) is widely used for medicinal purposes in many Asian countries due to its various bioactivities. A series of AA derivatives has been synthesized in attempts to improve its therapeutic potencies. Herein we investigated the anti-tumor activities of N-(2α,3β,23-acetoxyurs-12-en-28-oyl)-l-proline methyl ester (AA-PMe), a novel AA derivative. AA-PMe exhibited a stronger anti-cancer activity than its parent compound AA. AA-PMe inhibited the proliferation of SGC7901 and HGC27 human gastric cancer cells in a dose-dependent manner but had no significant toxicity in human gastric mucosa epithelial cells (GES-1). AA-PMe induced cell cycle arrest in G0/G1 phase and blocked G1-S transition, which correlated well with marked decreases in levels of cyclin D1, cyclin-dependent kinase CKD4, and phosphorylated retinoblastoma protein, and increase in cyclin-dependent kinase inhibitor P15. Further, AA-PMe induced apoptosis of human gastric cancer cells by affecting Bcl-2, Bax, c-Myc, and caspase-3. Moreover, AA-PMe suppressed the migration and invasion of human gastric cancer cells (SGC7901 and HGC27) cells by downregulating the expression of MMP-2 and MMP-9. Overall, this study investigated the potential anti-cancer activities of AA-PMe including inducing apoptosis and suppressing proliferation, migration and invasion of gastric cancer cells, as well as the underlying mechanisms, suggesting that AA-PMe is a promising anti-cancer drug candidate in gastric cancer therapy.

  4. AA-PMe, a novel asiatic acid derivative, induces apoptosis and suppresses proliferation, migration, and invasion of gastric cancer cells

    PubMed Central

    Jing, Yue; Wang, Gang; Ge, Ying; Xu, Minjie; Tang, Shuainan; Gong, Zhunan

    2016-01-01

    Asiatic acid (AA; 2α,3β,23-trihydroxyurs-12-ene-28-oic acid) is widely used for medicinal purposes in many Asian countries due to its various bioactivities. A series of AA derivatives has been synthesized in attempts to improve its therapeutic potencies. Herein we investigated the anti-tumor activities of N-(2α,3β,23-acetoxyurs-12-en-28-oyl)-l-proline methyl ester (AA-PMe), a novel AA derivative. AA-PMe exhibited a stronger anti-cancer activity than its parent compound AA. AA-PMe inhibited the proliferation of SGC7901 and HGC27 human gastric cancer cells in a dose-dependent manner but had no significant toxicity in human gastric mucosa epithelial cells (GES-1). AA-PMe induced cell cycle arrest in G0/G1 phase and blocked G1-S transition, which correlated well with marked decreases in levels of cyclin D1, cyclin-dependent kinase CKD4, and phosphorylated retinoblastoma protein, and increase in cyclin-dependent kinase inhibitor P15. Further, AA-PMe induced apoptosis of human gastric cancer cells by affecting Bcl-2, Bax, c-Myc, and caspase-3. Moreover, AA-PMe suppressed the migration and invasion of human gastric cancer cells (SGC7901 and HGC27) cells by downregulating the expression of MMP-2 and MMP-9. Overall, this study investigated the potential anti-cancer activities of AA-PMe including inducing apoptosis and suppressing proliferation, migration and invasion of gastric cancer cells, as well as the underlying mechanisms, suggesting that AA-PMe is a promising anti-cancer drug candidate in gastric cancer therapy. PMID:27073325

  5. Delaying cluster growth of ionotropic induced alginate gelation by oligoguluronate.

    PubMed

    Padoł, Anna Maria; Maurstad, Gjertrud; Draget, Kurt Ingar; Stokke, Bjørn Torger

    2015-11-20

    Alginates form gels in the presence of various divalent ions, such as Ca(2+) that mediate lateral association of chain segments. Various procedures exist that introduce Ca(2+) to yield alginate hydrogels with overall homogeneous or controlled gradients in the concentration profiles. In the present study, the effect of adding oligomers of α-l-guluronic acid (oligoGs) to gelling solutions of alginate was investigated by determination of the cluster growth stimulated by in situ release of Ca(2+). Three different alginate samples varying in fraction of α-l-guluronic acid and molecular weights were employed. The cluster growth was determined for both pure alginates and alginates with two different concentrations of the oligoGs employing dynamic light scattering. The results show that addition of oligoG slows down the cluster growth, the more efficient for the alginates with higher fraction of α-l-guluronic acid, and the higher molecular weight. The efficiency in delaying and slowing the cluster growth induced by added oligoG were discussed in view of the molecular parameters of the alginates. These results show that oligoG can be added to alginate solutions to control the cluster growth and eventually also transition to the gel state. Quantitative relation between the concentration of added oligoG, type and molecular weight of the alginate, and concentration, can be employed as guidelines in tuning alginate cluster growth with specific properties.

  6. Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

    PubMed

    Hu, Yang; Ma, Shanshan; Yang, Zhuohong; Zhou, Wuyi; Du, Zhengshan; Huang, Jian; Yi, Huan; Wang, Chaoyang

    2016-04-01

    In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of D-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications.

  7. Injectable in situ self-cross-linking hydrogels based on poly(L-glutamic acid) and alginate for cartilage tissue engineering.

    PubMed

    Yan, Shifeng; Wang, Taotao; Feng, Long; Zhu, Jie; Zhang, Kunxi; Chen, Xuesi; Cui, Lei; Yin, Jingbo

    2014-12-08

    Injectable hydrogels as an important biomaterial class have been widely used in regenerative medicine. A series of injectable poly(l-glutamic acid)/alginate (PLGA/ALG) hydrogels were fabricated by self-cross-linking of hydrazide-modified poly(l-glutamic acid) (PLGA-ADH) and aldehyde-modified alginate (ALG-CHO). Both the degree of PLGA modification and the oxidation degree of ALG-CHO could be adjusted by the amount of activators and sodium periodate, respectively. The effect of the solid content of the hydrogels and oxidation degree of ALG-CHO on the gelation time, equilibrium swelling, mechanical properties, microscopic morphology, and in vitro degradation of the hydrogels was examined. Encapsulation of rabbit chondrocytes within hydrogels showed viability of the entrapped cells and good biocompatibility of the injectable hydrogels. A preliminary study exhibited injectability and rapid in vivo gel formation, as well as mechanical stability, cell ingrowth, and ectopic cartilage formation. The injectable PLGA/ALG hydrogels demonstrated attractive properties for future application in a variety of pharmaceutical delivery and tissue engineering, especially in cartilage tissue engineering.

  8. New insights into Pseudomonas fluorescens alginate biosynthesis relevant for the establishment of an efficient production process for microbial alginates.

    PubMed

    Maleki, Susan; Mærk, Mali; Hrudikova, Radka; Valla, Svein; Ertesvåg, Helga

    2017-07-25

    Alginate denotes a family of linear polysaccharides with a wide range of industrial and pharmaceutical applications. Presently, all commercially available alginates are manufactured from brown algae. However, bacterial alginates have advantages with regard to compositional homogeneity and reproducibility. In order to be able to design bacterial strains that are better suited for industrial alginate production, defining limiting factors for alginate biosynthesis is of vital importance. Our group has been studying alginate biosynthesis in Pseudomonas fluorescens using several complementary approaches. Alginate is synthesised and transported out of the cell by a multiprotein complex spanning from the inner to the outer membrane. We have developed an immunogold labelling procedure in which the porin AlgE, as a part of this alginate factory, could be detected by transmission electron microscopy. No time-dependent correlation between the number of such factories on the cell surface and alginate production level was found in alginate-producing strains. Alginate biosynthesis competes with the central carbon metabolism for the key metabolite fructose 6-phosphate. In P. fluorescens, glucose, fructose and glycerol, are metabolised via the Entner-Doudoroff and pentose phosphate pathways. Mutational analysis revealed that disruption of the glucose 6-phosphate dehydrogenase gene zwf-1 resulted in increased alginate production when glycerol was used as carbon source. Furthermore, alginate-producing P. fluorescens strains cultivated on glucose experience acid stress due to the simultaneous production of alginate and gluconate. The combined results from our studies strongly indicate that the availability of fructose 6-phosphate and energy requires more attention in further research aimed at the development of an optimised alginate production process.

  9. Calcium alginate bead immobilization of cells containing tyrosine ammonia lyase activity for use in the production of p-hydroxycinnamic acid.

    PubMed

    Trotman, Robert J; Camp, Carl E; Ben-Bassat, Arie; DiCosimo, Robert; Huang, Lixuan; Crum, Grace A; Sariaslani, F Sima; Haynie, Sharon L

    2007-01-01

    An Escherichia coli catalyst with tyrosine ammonia lyase activity (TAL) has been stabilized for repeated use in batch conversions of high tyrosine solids to p-hydroxycinnamic acid (pHCA). The TAL biocatalyst was stabilized by controlling the reaction pH to 9.8 +/- 0.1 and immobilizing the cells within a calcium alginate matrix that was cross-linked with glutaraldehyde and polyethyleneimine (GA/PEI). We found a GA range where the bead-encapsulated TAL was not inactivated, and the resulting cross-linking provided the beads with the mechanical stability necessary for repeated use in consecutive batch reactions with catalyst recycle. The GA/PEI calcium alginate TAL catalyst was used in 41 1-L batch reactions where 50 g L(-1) tyrosine was converted to 39 +/- 4 g L(-1) pHCA in each batch. The practical usefulness and ease of this process was demonstrated by scaling up the TAL bead immobilization and using the immobilized TAL catalyst in four 125-L bioconversion reactions to produce over 12 kg of purified pHCA.

  10. Alginate-polyester comacromer based hydrogels as physiochemically and biologically favorable entities for cardiac tissue engineering.

    PubMed

    Thankam, Finosh G; Muthu, Jayabalan

    2015-11-01

    The physiochemical and biological responses of tissue engineering hydrogels are crucial in determining their desired performance. A hybrid comacromer was synthesized by copolymerizing alginate and poly(mannitol fumarate-co-sebacate) (pFMSA). Three bimodal hydrogels pFMSA-AA, pFMSA-MA and pFMSA-NMBA were synthesized by crosslinking with Ca(2+) and vinyl monomers acrylic acid (AA), methacrylic acid (MA) and N,N'-methylene bisacrylamide (NMBA), respectively. Though all the hydrogels were cytocompatible and exhibited a normal cell cycle profile, pFMSA-AA exhibited superior physiochemical properties viz non-freezable water content (58.34%) and water absorption per unit mass (0.97 g water/g gel) and pore length (19.92±3.91 μm) in comparing with other two hydrogels. The increased non-freezable water content and water absorption of pFMSA-AA hydrogels greatly influenced its biological performance, which was evident from long-term viability assay and cell cycle proliferation. The physiochemical and biological favorability of pFMSA-AA hydrogels signifies its suitability for cardiac tissue engineering.

  11. The effects of olive oil emulsified alginate on the physico-chemical, sensory, microbial, and fatty acid profiles of low-salt, inulin-enriched sausages.

    PubMed

    Beriain, M J; Gómez, I; Petri, E; Insausti, K; Sarriés, M V

    2011-05-01

    This paper examines variations in the quality of low-salt, inulin enriched Pamplona-style chorizo, in which some of the pork back fat was replaced with olive oil. Four different sausage formulations were prepared in which 50% of the pork back fat was replaced with olive oil emulsified with alginate and 58% of the sodium chloride was replaced with 20% potassium chloride and 38% calcium chloride. Four lots were prepared, three with 3%, 6% and 10% proportions of added inulin were labeled O-I 3%, O-I 6% and O-I 10%, respectively; while one, lot O, was without inulin. These four formulations were compared with a control manufactured according to the traditional formula using pork back fat. The various lots were tested for proximate analysis, pH, processing loss, water activity, lactic acid bacteria, Salmonella and Listeria monocytogenes, physico-chemical composition, instrumental colour (CIE L*a*b*), texture profile and fatty acid composition during mixing and at days 3, 10, 17, 24 and 31 of the drying process. A sensory evaluation was also performed by a seven-member trained panel, to obtain a descriptive analysis of the taste, texture and appearance of the product. The addition of olive oil alginate emulsion and inulin, O-I 6%, resulted in a low-salt, reduced-fat product (20% less fat than traditional sausage), richer in monounsaturated fatty acids (10%), while retaining sensory notes similar to those of the traditional chorizo used as a control and achieved a good acceptability rating.

  12. Relevance of rheological properties of sodium alginate in solution to calcium alginate gel properties.

    PubMed

    Fu, Shao; Thacker, Ankur; Sperger, Diana M; Boni, Riccardo L; Buckner, Ira S; Velankar, Sachin; Munson, Eric J; Block, Lawrence H

    2011-06-01

    The purpose of this study is to determine whether sodium alginate solutions' rheological parameters are meaningful relative to sodium alginate's use in the formulation of calcium alginate gels. Calcium alginate gels were prepared from six different grades of sodium alginate (FMC Biopolymer), one of which was available in ten batches. Cylindrical gel samples were prepared from each of the gels and subjected to compression to fracture on an Instron Universal Testing Machine, equipped with a 1-kN load cell, at a cross-head speed of 120 mm/min. Among the grades with similar % G, (grades 1, 3, and 4), there is a significant correlation between deformation work (L(E)) and apparent viscosity (η(app)). However, the results for the partial correlation analysis for all six grades of sodium alginate show that L(E) is significantly correlated with % G, but not with the rheological properties of the sodium alginate solutions. Studies of the ten batches of one grade of sodium alginate show that η(app) of their solutions did not correlate with L(E) while tan δ was significantly, but minimally, correlated to L(E). These results suggest that other factors--polydispersity and the randomness of guluronic acid sequencing--are likely to influence the mechanical properties of the resultant gels. In summary, the rheological properties of solutions for different grades of sodium alginate are not indicative of the resultant gel properties. Inter-batch differences in the rheological behavior for one specific grade of sodium alginate were insufficient to predict the corresponding calcium alginate gel's mechanical properties.

  13. Engineered yeast whole-cell biocatalyst for direct degradation of alginate from macroalgae and production of non-commercialized useful monosaccharide from alginate.

    PubMed

    Takagi, Toshiyuki; Yokoi, Takahiro; Shibata, Toshiyuki; Morisaka, Hironobu; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2016-02-01

    Alginate is a major component of brown macroalgae. In macroalgae, an endolytic alginate lyase first degrades alginate into oligosaccharides. These oligosaccharides are further broken down into monosaccharides by an exolytic alginate lyase. In this study, genes encoding various alginate lyases derived from alginate-assimilating marine bacterium Saccharophagus degradans were isolated, and their enzymes were displayed using the yeast cell surface display system. Alg7A-, Alg7D-, and Alg18J-displaying yeasts showed endolytic alginate lyase activity. On the other hand, Alg7K-displaying yeast showed exolytic alginate lyase activity. Alg7A, Alg7D, Alg7K, and Alg18J, when displayed on yeast cell surface, demonstrated both polyguluronate lyase and polymannuronate lyase activities. Additionally, polyguluronic acid could be much easily degraded by Alg7A, Alg7K, and Alg7D than polymannuronic acid. In contrast, polymannuronic acid could be much easily degraded by Alg18J than polyguluronic acid. We further constructed yeasts co-displaying endolytic and exolytic alginate lyases. Degradation efficiency by the co-displaying yeasts were significantly higher than single alginate lyase-displaying yeasts. Alg7A/Alg7K co-displaying yeast had maximum alginate degrading activity, with production of 1.98 g/L of reducing sugars in a 60-min reaction. This system developed, along with our findings, will contribute to the efficient utilization and production of useful and non-commercialized monosaccharides from alginate by Saccharomyces cerevisiae.

  14. Experimental study of albumin and lysozyme adsorption onto acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) surfaces.

    PubMed

    Moradi, Omid; Modarress, Hamid; Noroozi, Mehdi

    2004-03-01

    Many commercial soft contact lenses are based on poly-2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) hydrogels. The adsorption of proteins, albumin and lysozyme, on such contact lens surfaces may cause problems in their applications. In this work the adsorption of proteins, albumin and lysozyme, on hydrogel surfaces, AA and HEMA, was investigated as a function of concentration of protein. Also the effects of pH and ionic strength of protein solution on the adsorption of protein were examined. The obtained results indicated that the degree of adsorption of protein increased with the concentration of protein, and the adsorption of albumin on HEMA surface at the studied pHs (6.2-8.6) was higher than AA surface, whereas the adsorption of lysozyme on AA surface at the same pHs was higher than HEMA. The change in ionic strength of protein solution affected the proteins adsorption on both AA and HEMA surfaces. Also, the amount of sodium ions deposited on the AA surface was much higher than HEMA surface. This effect can be related to the negative surface charge of AA and its higher tendency for adsorption of sodium ions compared to the HEMA surface.

  15. Use of alginate beads as carriers for lactic acid bacteria in a structured system and preliminary validation in a meat product.

    PubMed

    Corbo, Maria Rosaria; Bevilacqua, Antonio; Speranza, Barbara; Di Maggio, Barbara; Gallo, Mariangela; Sinigaglia, Milena

    2016-01-01

    This paper proposes the microencapsulation into alginate beads of 4 isolates of lactic acid bacteria (Lactobacillus spp.), previously isolated from pork meat. First, the beads were studied in relation to the encapsulation yield (EY), kinetic of cell release in a structured system, and survival throughout bead storage at 4 °C. EY was 93-96% and the survival of the encapsulated microorganisms was variable, with two isolates showing a bacterial population of 6.1-6.9 log cfu/g after 35 days under refrigerated conditions. Thereafter, the paper addressed a preliminary validation in a meat model system, containing salt, nitrites and nitrates, lactose, pepper, and then in a commercial preparation of pork meat. For the validation in pork meat, free cells were used as controls. Cell released from beads were able to achieve a significant acidification; in particular, after 7 days they showed the same results of free cells.

  16. Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization

    PubMed Central

    Takahashi, Mami; Tanaka, Reiji; Miyake, Hideo; Shibata, Toshiyuki; Chow, Seinen; Kuroda, Kouichi; Ueda, Mitsuyoshi; Takeyama, Haruko

    2016-01-01

    Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a primary alginate degradation pathway with only single homologs of an endo- and exo-type alginate lyase, AlyFRA and AlyFRB, which is uncommon among such bacteria. Subsequent functional analysis showed that both enzymes were extremely efficient to depolymerize alginate suggesting evolutionary interests in the acquirement of these enzymes. The exo-type alginate lyase, AlyFRB in particular could depolymerize alginate without producing intermediate products making it a highly efficient enzyme for the production of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Based on our findings, we believe that the discovery of Falsirhodobacter sp. alg1 and its alginolytic genes hints at the potentiality of a more diverse and unique population of alginate-degrading bacteria. PMID:27176711

  17. Stability of 100 homo and heterotypic coiled-coil a-a' pairs for ten amino acids (A, L, I, V, N, K, S, T, E, and R).

    PubMed

    Acharya, Asha; Rishi, Vikas; Vinson, Charles

    2006-09-26

    We present the thermal stability monitored by circular dichroism (CD) spectroscopy at 222 nm of 100 heterodimers that contain all possible coiled-coil a-a' pairs for 10 amino acids (I, V, L, N, A, K S, T, E, and R). This includes the stability of 36 heterodimers for 6 amino acids (I, V, L, N, A, and K) previously described and 64 new heterodimers including the 4 amino acids (S, T, E, and R). We have calculated a double mutant alanine thermodynamic cycle to determine a-a' pair coupling energies to evaluate which a-a' pairs encourage specific dimerization partners. The four new homotypic a-a' pairs (T-T, S-S, R-R, E-E) are repulsive relative to A-A and have destabilizing coupling energies. Among the 90 heterotypic a-a' pairs, the stabilizing coupling energies contain lysine or arginine paired with either an aliphatic or a polar amino acid. The range in coupling energies for each amino acid reveals its potential to regulate dimerization specificity. The a-a' pairs containing isoleucine and asparagine have the greatest range in coupling energies and thus contribute dramatically to dimerization specificity, which is to encourage homodimerization. In contrast, the a-a' pairs containing charged amino acids (K, R, and E) show the least range in coupling energies and promiscuously encourage heterodimerization.

  18. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    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.

  19. Method for quantifying alginate and determining release from a food vehicle in gastrointestinal digesta.

    PubMed

    Houghton, David; Wilcox, Matthew D; Brownlee, Iain A; Chater, Peter; Seal, Chris J; Pearson, Jeffrey P

    2014-05-15

    To assess the efficacy of alginate as a modifier of enzyme activity, a suitable method to quantify its release must be developed. This paper develops and assesses the ability of the Periodic Acid Schiffs (PAS) assay to quantify alginate, and its release from bread during digestion in a model gut. Control and alginate enriched (4% w/w wet dough) bread were used. A model gut replicating the mouth, stomach and small intestines was used. Standard curves were created for alginate in deionised H2O and model gut solutions using a modified PAS to remove interference. The PAS assay quantified alginate with excellent linearity (R(2)=0.99), and optical density range (0.02-0.5). There was a significant difference in alginate release at 180 min compared to 0 and 60 min. The data indicate the modified PAS assay is a simple method for quantifying alginate release and release rate from alginate enriched products.

  20. Synergism and Rules of the new Combination drug Yiqijiedu Formulae (YQJD) on Ischemic Stroke based on amino acids (AAs) metabolism

    PubMed Central

    Gao, Jian; Chen, Chang; Chen, Jian-Xin; Wen, Li-Mei; Yang, Geng-Liang; Duan, Fei-Peng; Huang, Zhi-Ying; Li, De-Feng; Yu, Ding-Rong; Yang, Hong-Jun; Li, Shao-Jing

    2014-01-01

    The use of combination drugs is considered to be a promising strategy to control complex diseases such as ischemic stroke. The detection of metabolites has been used as a versatile tool to reveal the potential mechanism of diverse diseases. In this study, the levels of 12 endogenous AAs were simultaneously determined quantitatively in the MCAO rat brain using RRLC-QQQ method. Seven AAs were chosen as the potential biomarkers, and using PLS-DA analysis, the effects of the new combination drug YQJD, which is composed of ginsenosides, berberine, and jasminoidin, on those 7 AAs were evaluated. Four AAs, glutamic acid, homocysteine, methionine, and tryptophan, which changed significantly in the YQJD-treated groups compared to the vehicle groups (P < 0.05), were identified and designated as the AAs to use to further explore the synergism of YQJD. The result of a PCA showed that the combination of these three drugs exhibits the strongest synergistic effect compared to other combination groups and that ginsenosides might play a pivotal role, especially when combined with jasminoidin. We successfully explored the synergetic mechanism of multi-component and provided a new method for evaluating the integrated effects of combination drugs in the treatment of complex diseases. PMID:24889025

  1. Preparation methods of alginate nanoparticles.

    PubMed

    Paques, Jerome P; van der Linden, Erik; van Rijn, Cees J M; Sagis, Leonard M C

    2014-07-01

    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 nanocapsules, and complex formation in an aqueous solution is used to form alginate nano-aggregates. In a second method w/o emulsification coupled with gelation of the alginate emulsion droplet can be used to form alginate nanospheres. We review advantages and disadvantages of these methods, and give an overview of the properties of the alginate particles produced with these methods.

  2. The dye or humic acid water treatment and membrane fouling by polyaluminum chloride composited with sodium alginate in coagulation-ultrafiltration process.

    PubMed

    Wang, Yan; Zhang, Feng; Chu, Yongbao; Gao, Baoyu; Yue, Qinyan

    2013-01-01

    Composite flocculants have been extensively studied and applied in recent years in order to improve the water treatment efficiency. In this study, a new composite flocculant prepared by polyaluminum chloride (PAC) and sodium alginate (SA) was used to treat dye and humic acid water in the coagulation-ultrafiltration process. The subsequent effects of PAC/SA on ultrafiltration membrane fouling were investigated by calculating the Modified Fouling Index (MFI). The results showed that the application of PAC/SA could not only restrict the membrane fouling but also improve the removal efficiency of the coagulation-ultrafiltration process. MFI of PAC/SA was the lowest, followed by PAC and the raw water for coagulated effluents filtered by ultrafiltration membrane. For example, MFI of PAC/SA was 0.40 s mL(-2) for reactive blue KGL (denoted as RB-KGL) treatment, while that of PAC was 2.26 s mL(-2). The removal efficiencies were improved as coagulation was used as pretreatment of ultrafiltration membrane. And PAC/SA could form the higher removal efficiency than PAC, especially for RB-KGL. The color removal efficiency of PAC/SA was 96.36% for RB-KGL treated by coagulation-ultrafiltration process, which was higher than that of PAC (85.62%).

  3. Fabrication of granular activated carbons derived from spent coffee grounds by entrapment in calcium alginate beads for adsorption of acid orange 7 and methylene blue.

    PubMed

    Jung, Kyung-Won; Choi, Brian Hyun; Hwang, Min-Jin; Jeong, Tae-Un; Ahn, Kyu-Hong

    2016-11-01

    Biomass-based granular activated carbon was successfully prepared by entrapping activated carbon powder derived from spent coffee grounds into calcium-alginate beads (SCG-GAC) for the removal of acid orange 7 (AO7) and methylene blue (MB) from aqueous media. The dye adsorption process is highly pH-dependent and essentially independent of ionic effects. The adsorption kinetics was satisfactorily described by the pore diffusion model, which revealed that pore diffusion was the rate-limiting step during the adsorption process. The equilibrium isotherm and isosteric heat of adsorption indicate that SCG-GAC possesses an energetically heterogeneous surface and operates via endothermic process in nature. The maximum adsorption capacities of SCG-GAC for AO7 (pH 3.0) and MB (pH 11.0) adsorption were found to be 665.9 and 986.8mg/g at 30°C, respectively. Lastly, regeneration tests further confirmed that SCG-GAC has promising potential in its reusability, showing removal efficiency of more than 80% even after seven consecutive cycles.

  4. Impact of feed counterion addition and cyclone type on aerodynamic behavior of alginic-atenolol microparticles produced by spray drying.

    PubMed

    Ceschan, Nazareth Eliana; Bucalá, Verónica; Ramírez-Rigo, María Verónica; Smyth, Hugh David Charles

    2016-12-01

    The inhalatory route has emerged as an interesting non-invasive alternative for drug delivery. This allows both pulmonary (local) and systemic treatments (via alveolar absorption). Further advantages in terms of stability, dose and patient preference have often lead researchers to focus on dry powder inhaler delivery systems. Atenolol is an antihypertensive drug with low oral bioavailability and gastrointestinal side effects. Because atenolol possesses adequate permeation across human epithelial membranes, it has been proposed as a good candidate for inhalatory administration. In a previous work, atenolol was combined with alginic acid (AA) and microparticles were developed using spray-drying (SD) technology. Different AA/atenolol ratios, total feed solid content and operative variables were previously explored. In order to improve particle quality for inhalatory administration and the SD yield, in this work the AA acid groups not neutralized by atenolol were kept either free or neutralized to pH∼7 and two different SD cyclones were used. Particle morphology, flow properties, moisture uptake and in vitro aerosolization behavior at different pressure drops were studied. When the AA acid groups were neutralized, particle size decreased as a consequence of the lower feed viscosity. The SD yield and in vitro particle deposition significantly increased when a high performance cyclone was employed, and even when lactose carrier particles were not used. Although the in vitro particle deposition decreased when the storage relative humidity increased, the developed SD powders showed adequate characteristics to be administered by inhalatory route up to storage relative humidities of about 60%.

  5. Alginate gels with a combination of calcium and chitosan oligomer mixtures as crosslinkers.

    PubMed

    Feng, Yiming; Kopplin, Georg; Sato, Kimihiko; Draget, Kurt I; Vårum, Kjell M

    2017-01-20

    Alginates are polysaccharides that are widely used in relation to their ability to form gels. Recently we reported that alginates may also form gels with chitosan oligomers as crosslinkers (Khong, Aarstad, Skjåk-Bræk, Draget, & Vårum, 2013). The purpose of the present study was to characterize alginate gels crosslinked with calcium and chitosan oligomers. Using two different alginates of similar molecular weights but different chemical composition, i.e. guluronic acid content of 46 and 68%, we found that both alginates could form homogeneous gels with calcium and chitosan oligomers separately and without syneresis. Systematic combinations of calcium and chitosan oligomers as crosslinkers were tested, showing that up to 50% of the calcium could be substituted with chitosan oligomers without reduction in gel strength or increased syneresis for the alginate with the lowest guluronic acid content. Furthermore, the kinetics of the combined gels were different from pure calcium alginate gels.

  6. A Novel Aldo-Keto Reductase, HdRed, from the Pacific Abalone Haliotis discus hannai, Which Reduces Alginate-derived 4-Deoxy-l-erythro-5-hexoseulose Uronic Acid to 2-Keto-3-deoxy-d-gluconate*

    PubMed Central

    Mochizuki, Shogo; Nishiyama, Ryuji; Inoue, Akira; Ojima, Takao

    2015-01-01

    Abalone feeds on brown seaweeds and digests seaweeds' alginate with alginate lyases (EC 4.2.2.3). However, it has been unclear whether the end product of alginate lyases (i.e. unsaturated monouronate-derived 4-deoxy-l-erythro-5-hexoseulose uronic acid (DEH)) is assimilated by abalone itself, because DEH cannot be metabolized via the Embden-Meyerhof pathway of animals. Under these circumstances, we recently noticed the occurrence of an NADPH-dependent reductase, which reduced DEH to 2-keto-3-deoxy-d-gluconate, in hepatopancreas extract of the pacific abalone Haliotis discus hannai. In the present study, we characterized this enzyme to some extent. The DEH reductase, named HdRed in the present study, could be purified from the acetone-dried powder of hepatopancreas by ammonium sulfate fractionation followed by conventional column chromatographies. HdRed showed a single band of ∼40 kDa on SDS-PAGE and reduced DEH to 2-keto-3-deoxy-d-gluconate with an optimal temperature and pH at around 50 °C and 7.0, respectively. HdRed exhibited no appreciable activity toward 28 authentic compounds, including aldehyde, aldose, ketose, α-keto-acid, uronic acid, deoxy sugar, sugar alcohol, carboxylic acid, ketone, and ester. The amino acid sequence of 371 residues of HdRed deduced from the cDNA showed 18–60% identities to those of aldo-keto reductase (AKR) superfamily enzymes, such as human aldose reductase, halophilic bacterium reductase, and sea hare norsolorinic acid (a polyketide derivative) reductase-like protein. Catalytic residues and cofactor binding residues known in AKR superfamily enzymes were fairly well conserved in HdRed. Phylogenetic analysis for HdRed and AKR superfamily enzymes indicated that HdRed is an AKR belonging to a novel family. PMID:26555267

  7. An amino acid-based oral rehydration solution (AA-ORS) enhanced intestinal epithelial proliferation in mice exposed to radiation

    PubMed Central

    Yin, Liangjie; Gupta, Reshu; Vaught, Lauren; Grosche, Astrid; Okunieff, Paul; Vidyasagar, Sadasivan

    2016-01-01

    Destruction of clonogenic cells in the crypt following irradiation are thought to cause altered gastrointestinal function. Previously, we found that an amino acid-based oral rehydration solution (AA-ORS) improved gastrointestinal function in irradiated mice. However, the exact mechanisms were unknown. Electrophysiology, immunohistochemistry, qPCR, and Western blot analysis were used to determine that AA-ORS increased proliferation, maturation, and differentiation and improved electrolyte and nutrient absorption in irradiated mice. A single-hit, multi-target crypt survival curve showed a significant increase in crypt progenitors in irradiated mice treated with AA-ORS for six days (8.8 ± 0.4) compared to the saline-treated group (6.1 ± 0.3; P < 0.001) without a change in D0 (4.8 ± 0.1 Gy). The Dq values increased from 8.8 ± 0.4 Gy to 10.5 ± 0.5 Gy with AA-ORS treatment (P < 0.01), indicating an increased radiation tolerance of 1.7 Gy. We also found that AA-ORS treatment (1) increased Lgr5+, without altering Bmi1 positive cells; (2) increased levels of proliferation markers (Ki-67, p-Erk, p-Akt and PCNA); (3) decreased apoptosis markers, such as cleaved caspase-3 and Bcl-2; and (4) increased expression and protein levels of NHE3 and SGLT1 in the brush border membrane. This study shows that AA-ORS increased villus height and improved electrolyte and nutrient absorption. PMID:27876791

  8. Compatible compositions based on aqueous polyurethane dispersions and sodium alginate.

    PubMed

    Daemi, Hamed; Barikani, Mehdi; Barmar, Mohammad

    2013-01-30

    A series of aqueous polyurethane dispersions were synthesized by the reaction of polytetramethylene glycol and isophorone diisocyanate, extended with dimethylol propionic acid. Their chemical structures were characterized using FTIR, (1)H NMR, and (13)C NMR, and thermal properties were determined by DMTA. Then, a number of aqueous polyurethane dispersions-sodium alginate (PUD/SA) compositions were prepared by addition of sodium alginate solution with different concentrations into the aqueous polyurethane dispersion. Characterization of chemical structure and thermal properties of these blends were performed by FTIR, EDX and DMTA, respectively. The morphology of the alginate in polyurethane matrix was studied by SEM. The hydrophilicity of the prepared samples decreases by increasing the content of sodium alginate in blends. These observations were attributed to the increase of hydrophilicity of the blends as a consequence of addition of hydrophilic carboxylate, hydroxyl and ether functional groups of the alginate to them.

  9. Development of a sodium alginate-based organic/inorganic superabsorbent composite hydrogel for adsorption of methylene blue.

    PubMed

    Thakur, Sourbh; Pandey, Sadanand; Arotiba, Omotayo A

    2016-11-20

    Batch adsorption experiments were carried out for the removal of methylene blue (MB) cationic dye from aqueous solution using organic/inorganic hydrogel nanocomposite of titania incorporated sodium alginate crosslinked polyacrylic acid (SA-cl-poly(AA)-TiO2). The hydrogel was prepared by graft copolymerization of acrylic acid (AA) onto sodium alginate (SA) biopolymer in the presence of a crosslinking agent, a free radical initiator and TiO2 nanoparticles. The hydrogel exhibited a high swelling capacity of 412.98g/g. The factors influencing adsorption capacity of the absorbents such as pH of the dye solutions, initial concentration of the dye, amount of absorbents, and temperature were investigated and used to propose a possible mechanism of adsorption. The adsorption process concurs with a pseudo-second-order kinetics and with Langmuir isotherm equation. A very high adsorption capacity (Qmax=2257.36 (mg/g)) and a correlation coefficient of 0.998 calculated from isotherm equations show the high efficiency of the absorbent and thus expected to be a good candidate as an absorbent for water treatment.

  10. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... prepared by the neutralization of purified alginic acid with appropriate pH control agents. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 18, which is incorporated... food Maximum level of use in food (as served) (percent) Functional use Confections, frostings, §...

  11. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae... this chapter 0.6 Do. Fats and oils, § 170.3(n)(12) of this chapter 0.5 Do. Gelatins, puddings, §...

  12. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...-34-9) is the ammonium salt of alginic acid, a natural polyuronide constituent of certain brown algae..., § 170.3(n)(9) of this chapter 0.4 Stabilizer, thickener, § 170.3(o)(28) of this chapter. Fats and...

  13. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...-35-0) is the calcium salt of alginic acid, a natural polyuronide constituent of certain brown algae... this chapter 0.6 Do. Fats and oils, § 170.3(n)(12) of this chapter 0.5 Do. Gelatins, puddings, §...

  14. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...-34-9) is the ammonium salt of alginic acid, a natural polyuronide constituent of certain brown algae..., § 170.3(n)(9) of this chapter 0.4 Stabilizer, thickener, § 170.3(o)(28) of this chapter. Fats and...

  15. Design of an effective bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate (ATMP-FA) and optimization by Box-Behnken model for biodiesel esterification synthesis of oleic acid over ATMP-FA.

    PubMed

    Liu, Wei; Yin, Ping; Liu, Xiguang; Qu, Rongjun

    2014-12-01

    Biodiesel production has become an intense research area because of rapidly depleting energy reserves and increasing petroleum prices together with environmental concerns. This paper focused on the optimization of the catalytic performance in the esterification reaction of oleic acid for biodiesel production over the bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate ATMP-FA. The reaction parameters including catalyst amount, ethanol to oleic acid molar ratio and reaction temperature have been optimized by response surface methodology (RSM) using the Box-Behnken model. It was found that the reaction temperature was the most significant factor, and the best conversion ratio of oleic acid could reach 93.17% under the reaction conditions with 9.53% of catalyst amount and 8.62:1 of ethanol to oleic acid molar ratio at 91.0 °C. The research results show that two catalytic species could work cooperatively to promote the esterification reaction, and the bifunctional ATMP-FA is a potential catalyst for biodiesel production.

  16. Comparative study on the in vitro effects of Pseudomonas aeruginosa and seaweed alginates on human gut microbiota.

    PubMed

    Bai, Shaofeng; Chen, Huahai; Zhu, Liying; Liu, Wei; Yu, Hongwei D; Wang, Xin; Yin, Yeshi

    2017-01-01

    Alginates pertain to organic polysaccharides that have been extensively used in food- and medicine-related industries. The present study obtained alginates from an alginate overproducing Pseudomonas aeruginosa PAO1 mutant by screening transposon mutagenesis libraries. The interaction between bacterial and seaweed alginates and gut microbiota were further studied by using an in vitro batch fermentation system. Thin-layer chromatography (TLC) analysis indicated that both bacterial and seaweed alginates can be completely degraded by fecal bacteria isolated from study volunteers, indicating that a minor structural difference between bacterial and seaweed alginates (O-acetylation and lack of G-G blocks) didn't affect the digestion of alginates by human microbiota. Although, the digestion of bacterial and seaweed alginates was attributed to different Bacteroides xylanisolvens strains, they harbored similar alginate lyase genes. Genus Bacteroides with alginate-degrading capability were enriched in growth medium containing bacterial or seaweed alginates after in vitro fermentation. Short-chain fatty acid (SCFA) production in both bacterial and seaweed alginates was also comparable, but was significantly higher than the same medium using starch. In summary, the present study has isolated an alginate-overproducing P. aeruginosa mutant strain. Both seaweed and bacterial alginates were degraded by human gut microbiota, and their regulatory function on gut microbiota was similar.

  17. Comparative study on the in vitro effects of Pseudomonas aeruginosa and seaweed alginates on human gut microbiota

    PubMed Central

    Bai, Shaofeng; Chen, Huahai; Zhu, Liying; Liu, Wei; Yu, Hongwei D.; Wang, Xin; Yin, Yeshi

    2017-01-01

    Alginates pertain to organic polysaccharides that have been extensively used in food- and medicine-related industries. The present study obtained alginates from an alginate overproducing Pseudomonas aeruginosa PAO1 mutant by screening transposon mutagenesis libraries. The interaction between bacterial and seaweed alginates and gut microbiota were further studied by using an in vitro batch fermentation system. Thin-layer chromatography (TLC) analysis indicated that both bacterial and seaweed alginates can be completely degraded by fecal bacteria isolated from study volunteers, indicating that a minor structural difference between bacterial and seaweed alginates (O-acetylation and lack of G-G blocks) didn’t affect the digestion of alginates by human microbiota. Although, the digestion of bacterial and seaweed alginates was attributed to different Bacteroides xylanisolvens strains, they harbored similar alginate lyase genes. Genus Bacteroides with alginate-degrading capability were enriched in growth medium containing bacterial or seaweed alginates after in vitro fermentation. Short-chain fatty acid (SCFA) production in both bacterial and seaweed alginates was also comparable, but was significantly higher than the same medium using starch. In summary, the present study has isolated an alginate-overproducing P. aeruginosa mutant strain. Both seaweed and bacterial alginates were degraded by human gut microbiota, and their regulatory function on gut microbiota was similar. PMID:28170428

  18. Use of laboratory-grown bacterial alginate in copper removal.

    PubMed

    Kivilcimdan Moral, Ç; Doğan, Ö; Sanin, F D

    2012-01-01

    Industrial production leads to toxic heavy metal pollution in water bodies. Copper is one of the examples that requires removal from effluents before being discharged. It is difficult and sometimes very expensive to remove toxic heavy metals by conventional treatment techniques. This study aims to remove copper by the use of bacterial alginate as a non-conventional technique. Bacterial alginates (natural polymers composed of mannuronic and guluronic acid monomers) were synthesized by Azotobacter vinelandii ATCC(®) 9046 in a laboratory fermentor under controlled environmental conditions. The alginates produced, with a range of different characteristics in terms of monomer distribution and viscosity, were investigated for maximum copper uptake capacities. The average copper uptake capacities of alginates produced were found to be about 1.90 mmol/L Cu(2+)/g alginate. Although the GG-block amount of alginates was varied from 12 to 87% and culture broth viscosities were changed within the range of 1.47 and 14 cP, neither the block distribution nor viscosities of alginate samples considerably affected the copper uptake of alginates.

  19. A synergistic combination of tetraethylorthosilicate and multiphosphonic acid offers excellent corrosion protection to AA1100 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Dalmoro, Viviane; dos Santos, João H. Z.; Armelin, Elaine; Alemán, Carlos; Azambuja, Denise S.

    2013-05-01

    This work describes a new mechanism for the incorporation of organophosphonic acid into silane self-assembly monolayers, which has been used to protect AA1100 aluminum alloy. The protection improvement has been attributed to the fact that phosphonic structures promote the formation of strongly bonded and densely packed monolayer films, which show higher surface coverage and better adhesion than conventional silane systems. In order to evaluate the linking chemistry offered by phosphonic groups, two functionalized organophosphonic groups have been employed, 1,2-diaminoethanetetrakis methylenephosphonic acid (EDTPO) and aminotrimethylenephosphonic acid (ATMP), and combined with tetraethylorthosilicate (TEOS) films prepared by sol-gel synthesis. Results suggest that phosphonic acids may interact with the surface through a monodentate and bidentate coordination mode and, in addition, form one or more strong and stable linkages with silicon through non-hydrolysable bonds. Therefore, the incorporation of a very low concentration of phosphonic acids on TEOS solutions favors the complete coverage of the aluminum substrate during the silanization process, which is not possible using TEOS alone. The linking capacity of phosphonic acid has been investigated by FTIR-RA spectroscopy, SEM and EDX analysis, X-ray photoelectron spectroscopy (XPS), and quantum mechanical calculations. Finally, electrochemical impedance spectroscopy has been used to study the corrosion protection revealing that EDTPO-containing films afforded more protection to the AA1100 substrate than ATMP-containing films.

  20. Characterization of AlgMsp, an Alginate Lyase from Microbulbifer sp. 6532A

    PubMed Central

    Swift, Steven M.; Hudgens, Jeffrey W.; Heselpoth, Ryan D.; Bales, Patrick M.; Nelson, Daniel C.

    2014-01-01

    Alginate is a polysaccharide produced by certain seaweeds and bacteria that consists of mannuronic acid and guluronic acid residues. Seaweed alginate is used in food and industrial chemical processes, while the biosynthesis of bacterial alginate is associated with pathogenic Pseudomonas aeruginosa. Alginate lyases cleave this polysaccharide into short oligo-uronates and thus have the potential to be utilized for both industrial and medicinal applications. An alginate lyase gene, algMsp, from Microbulbifer sp. 6532A, was synthesized as an E.coli codon-optimized clone. The resulting 37 kDa recombinant protein, AlgMsp, was expressed, purified and characterized. The alginate lyase displayed highest activity at pH 8 and 0.2 M NaCl. Activity of the alginate lyase was greatest at 50°C; however the enzyme was not stable over time when incubated at 50°C. The alginate lyase was still highly active at 25°C and displayed little or no loss of activity after 24 hours at 25°C. The activity of AlgMsp was not dependent on the presence of divalent cations. Comparing activity of the lyase against polymannuronic acid and polyguluronic acid substrates showed a higher turnover rate for polymannuronic acid. However, AlgMSP exhibited greater catalytic efficiency with the polyguluronic acid substrate. Prolonged AlgMsp-mediated degradation of alginate produced dimer, trimer, tetramer, and pentamer oligo-uronates. PMID:25409178

  1. Characterization of AlgMsp, an alginate lyase from Microbulbifer sp. 6532A.

    PubMed

    Swift, Steven M; Hudgens, Jeffrey W; Heselpoth, Ryan D; Bales, Patrick M; Nelson, Daniel C

    2014-01-01

    Alginate is a polysaccharide produced by certain seaweeds and bacteria that consists of mannuronic acid and guluronic acid residues. Seaweed alginate is used in food and industrial chemical processes, while the biosynthesis of bacterial alginate is associated with pathogenic Pseudomonas aeruginosa. Alginate lyases cleave this polysaccharide into short oligo-uronates and thus have the potential to be utilized for both industrial and medicinal applications. An alginate lyase gene, algMsp, from Microbulbifer sp. 6532A, was synthesized as an E.coli codon-optimized clone. The resulting 37 kDa recombinant protein, AlgMsp, was expressed, purified and characterized. The alginate lyase displayed highest activity at pH 8 and 0.2 M NaCl. Activity of the alginate lyase was greatest at 50°C; however the enzyme was not stable over time when incubated at 50°C. The alginate lyase was still highly active at 25°C and displayed little or no loss of activity after 24 hours at 25°C. The activity of AlgMsp was not dependent on the presence of divalent cations. Comparing activity of the lyase against polymannuronic acid and polyguluronic acid substrates showed a higher turnover rate for polymannuronic acid. However, AlgMSP exhibited greater catalytic efficiency with the polyguluronic acid substrate. Prolonged AlgMsp-mediated degradation of alginate produced dimer, trimer, tetramer, and pentamer oligo-uronates.

  2. Effects of extraction methods on molecular characteristics, antioxidant properties and immunomodulation of alginates from Sargassum angustifolium.

    PubMed

    Borazjani, Niloofar Jokar; Tabarsa, Mehdi; You, SangGuan; Rezaei, Masoud

    2017-03-29

    The relationship between molecular structure and bioactivity was evaluated for alginates obtained under different extraction methods (water, acid, alcalase and cellulase) from Sargassum angustifolium. The use of enzymes considerably reduced protein (from 14.58% to <0.4%) and polyphenol (from 16.0% to <1.7mg GA/g sample) contaminations of alginates compared to those of water and acid. The FT-IR spectrum revealed that extraction method did not affect the structure of the recovered alginates. The highest molecular weight (Mw) (557.1×10(3)g/mol) was found in acid treated alginate while the Mw of cellulase assistant alginate (356.2×10(3)g/mol) was the minimum. The SVg values varied from 2.79-5.17cm(3)/g revealing the loosed conformational structures of alcalase and cellulase assistant alginates. Alcalase assistant alginate stimulated RAW264.7 cells to release nitric oxide and inflammatory cytokines TNF-α, IL-1, IL-6, IL-10 and IL-12. Enzyme treated alginates showed maximum DPPH radical scavenging activity and reducing power. Therefore, the present results showed the determinant effect of pretreatment during the extraction process of alginate and the beneficial influence of enzymatic process when biological functions of alginates are of high interest in the industry.

  3. Synthesis of ST7612AA1, a Novel Oral HDAC Inhibitor, via Radical 
Thioacetic Acid Addition

    PubMed Central

    Battistuzzi, Gianfranco; Giannini, Giuseppe

    2016-01-01

    Abstract: Background In the expanding field of anticancer drugs, HDAC inhibitors are playing an increasingly important role. To date, four/five HDAC inhibitors have been approved by FDA. All these compounds fit the widely accepted HDAC inhibitors pharmacophore model characterized by a cap group, a linker chain and a zinc binding group (ZBG), able to bind the Zn2+ ion in a pocket of the HDAC active site. Romidepsin, a natural compound, is the only thiol derivative. We have selected a new class of synthetic HDAC inhibitors, the thio-ω(lactam-carboxamide) derivatives, with ST7612AA1 as drug candidate, pan-inhibitor active in the range of single- to two-digit nanomolar concentrations. Preliminary results of a synthetic optimization attempt towards a fast scale-up process are here proposed. Methods In the four steps of synthesis, from unsaturated amino acid intermediate to the final product, we explored different synthetic conditions in order to have a transferable process for a scale-up synthetic laboratory. Results In the first step, isobutyl chloroformate was used and, after a simple work up with 1M HCl, 2 (96% yield) was obtained as a white solid, which was used directly in the next step. For thioacetic acid addition to the double bond of intermediate 2, two different routes were possible, with addition reaction in the first (D’) or last step (D). Reactions of 2 to give 5 or of 4 to give ST7612AA1 were both performed in dioxane. Reactions were fast and did not need the usually advised radical quenching with cyclohexene. The corresponding products were obtained in good yields (step D’, 89%; step D, 81%) after a flash chromatography. Conclusion: ST7612AA1 , a thiol derivative prodrug of ST7464AA1, is the first of a new generation of HDAC inhibitors, very potent, orally administered, and well tolerated. Here, we have identified a synthetic route, competitive, versatile and easily transferable to industrial processes. PMID:27917100

  4. The Alginate Demonstration: Polymers, Food Science, and Ion Exchange

    NASA Astrophysics Data System (ADS)

    Waldman, Amy Sue; Schechinger, Linda; Govindarajoo, Geeta; Nowick, James S.; Pignolet, Louis H.

    1998-11-01

    We have recently devised a polymer demonstration involving the crosslinking and decrosslinking of alginate, a polysaccharide isolated from seaweed. The polymer is composed of D-mannuronic acid and L-guluronic acid subunits and is a component of cell walls. It is commonly used as a thickener in foods such as ice cream and fruit-filled snacks. For the demonstration, a 2% solution of sodium alginate is poured into a 1% solution of calcium chloride. Nontoxic calcium alginate "worms" form due to crosslinking of the polymer. Alternatively, the commercially available antacid Gaviscon can be used as a source of sodium alginate. The crosslinks can then be broken by shaking the worms in brine. The demonstration is a fine addition to any chemical educator's repertoire of polymer experiments.

  5. Molecular cloning and promoter analysis of the specific salicylic acid biosynthetic pathway gene phenylalanine ammonia-lyase (AaPAL1) from Artemisia annua.

    PubMed

    Zhang, Ying; Fu, Xueqing; Hao, Xiaolong; Zhang, Lida; Wang, Luyao; Qian, Hongmei; Zhao, Jingya

    2016-07-01

    Phenylalanine ammonia-lyase (PAL) is the key enzyme in the biosynthetic pathway of salicylic acid (SA). In this study, a full-length cDNA of PAL gene (named as AaPAL1) was cloned from Artemisia annua. The gene contains an open reading frame of 2,151 bps encoding 716 amino acids. Comparative and bioinformatics analysis revealed that the polypeptide protein of AaPAL1 was highly homologous to PALs from other plant species. Southern blot analysis revealed that it belonged to a gene family with three members. Quantitative RT-PCR analysis of various tissues of A. annua showed that AaPAL1 transcript levels were highest in the young leaves. A 1160-bp promoter region was also isolated resulting in identification of distinct cis-regulatory elements including W-box, TGACG-motif, and TC-rich repeats. Quantitative RT-PCR indicated that AaPAL1 was upregulated by salinity, drought, wounding, and SA stresses, which were corroborated positively with the identified cis-elements within the promoter region. AaPAL1 was successfully expressed in Escherichia. coli and the enzyme activity of the purified AaPAL1 was approximately 287.2 U/mg. These results substantiated the involvement of AaPAL1 in the phenylalanine pathway.

  6. Effect of adding amino acids residues in N- and C-terminus of Vip3Aa16 (L121I) toxin.

    PubMed

    Sellami, Sameh; Cherif, Marwa; Jamoussi, Kaïs

    2016-06-01

    To study the importance of N- and C-terminus of Bacillus thuringiensis Vip3Aa16 (L121I) toxin (88 kDa), a number of mutants were generated. The addition of two (2R: RS) or eleven (11R: RSRPGHHHHHH) amino acid residues at the Vip3Aa16 (L121I) C-terminus allowed to an unappropriated folding illustrated by the abundant presence of the 62 kDa proteolytic form. The produced Vip3Aa16 (L121I) full length form was less detected when increasing the number of amino acids residues in the C-terminus. Bioassays demonstrated that the growth of the lepidopteran Ephestia kuehniella was slightly affected by Vip3Aa16 (L121I)-2R and not affected by Vip3Aa16 (L121I)-11R. Additionally, the fusion at the Vip3Aa16 (L121I) N-terminus of 39 amino acids harboring the E. coli OmpA leader peptide and the His-tag sequence allowed to the increase of protease sensitivity of Vip3Aa16 (L121I) full length form, as only the 62 kDa proteolysis form was detected. Remarkably, this fused protein produced in Escherichia coli (E. coli) was biologically inactive toward Ephestia kuehniella larvae. Thus, the N-terminus of the protein is required to the accomplishment of the insecticidal activity of Vip3 proteins. This report serves as guideline for the study of Vip3Aa16 (L121I) protein stability and activity.

  7. In vivo degradation of alginate in the presence and in the absence of resistant starch.

    PubMed

    Jonathan, Melliana; Souza da Silva, Carol; Bosch, Guido; Schols, Henk; Gruppen, Harry

    2015-04-01

    This study evaluated the intestinal degradability of alginate during 74 days intake in pigs as models for humans. Diets contained pregelatinized starch, retrograded starch, alginate, or a mix of retrograded starch and alginate. Faeces were collected on day 1, 3, 7, 14, 39 and 74. Clear trends in intestinal alginate degradation were observed. Up to day 39, the total tract digestibility of alginate was limited (0.52 ± 0.10), and was lower with the inclusion of retrograded starch in the diet (0.34 ± 0.02). More than 90% of the faecal alginate was insoluble in water, which may explain the low digestibility of the alginate. The digestibility of mannuronic acid (M) was 2-3 times higher than that of guluronic acid (G). The changes of G:M ratio and the relative amounts of alginate oligosaccharides between day 39 and 74 indicated that the microbiota needed more than 39 days to adapt to alginate. This study demonstrated that in-depth analyses of dietary fibres are valuable in understanding the fate of the dietary fibres in the large intestine as it was shown that degradation of a dietary fibre depends not only on the properties of the fibre itself, but also on the other dietary fibres present in the diet and the adaptation time.

  8. AaCAT1 of the yellow fever mosquito, Aedes aegypti: a novel histidine-specific amino acid transporter from the SLC7 family.

    PubMed

    Hansen, Immo A; Boudko, Dmitri Y; Shiao, Shin-Hong; Voronov, Dmitri A; Meleshkevitch, Ella A; Drake, Lisa L; Aguirre, Sarah E; Fox, Jeffrey M; Attardo, Geoffrey M; Raikhel, Alexander S

    2011-03-25

    Insect yolk protein precursor gene expression is regulated by nutritional and endocrine signals. A surge of amino acids in the hemolymph of blood-fed female mosquitoes activates a nutrient signaling system in the fat bodies, which subsequently derepresses yolk protein precursor genes and makes them responsive to activation by steroid hormones. Orphan transporters of the SLC7 family were identified as essential upstream components of the nutrient signaling system in the fat body of fruit flies and the yellow fever mosquito, Aedes aegypti. However, the transport function of these proteins was unknown. We report expression and functional characterization of AaCAT1, cloned from the fat body of A. aegypti. Expression of AaCAT1 transcript and protein undergoes dynamic changes during postembryonic development of the mosquito. Transcript expression was especially high in the third and fourth larval stages; however, the AaCAT1 protein was detected only in pupa and adult stages. Functional expression and analysis of AaCAT1 in Xenopus oocytes revealed that it acts as a sodium-independent cationic amino acid transporter, with unique selectivity to L-histidine at neutral pH (K(0.5)(L-His) = 0.34 ± 0.07 mM, pH 7.2). Acidification to pH 6.2 dramatically increases AaCAT1-specific His(+)-induced current. RNAi-mediated silencing of AaCAT1 reduces egg yield of subsequent ovipositions. Our data show that AaCAT1 has notable differences in its transport mechanism when compared with related mammalian cationic amino acid transporters. It may execute histidine-specific transport and signaling in mosquito tissues.

  9. Alginate: A Versatile Biomaterial to Encapsulate Isolated Ovarian Follicles.

    PubMed

    Vanacker, Julie; Amorim, Christiani A

    2017-02-28

    In vitro culture of ovarian follicles isolated or enclosed in ovarian tissue fragments and grafting of isolated ovarian follicles represent a potential alternative to restore fertility in cancer patients who cannot undergo cryopreservation of embryos or oocytes or transplantation of frozen-thawed ovarian tissue. In this regard, respecting the three-dimensional (3D) architecture of isolated follicles is crucial to maintaining their proper follicular physiology. To this end, alginate hydrogel has been widely investigated using follicles from numerous animal species, yielding promising results. The goal of this review is therefore to provide an overview of alginate applications utilizing the biomaterial as a scaffold for 3D encapsulation of isolated ovarian follicles. Different methods of isolated follicle encapsulation in alginate are discussed in this review, as its use of 3D alginate culture systems as a tool for in vitro follicle analysis. Possible improvements of this matrix, namely modification with arginine-glycine-aspartic acid peptide or combination with fibrin, are also summarized. Encouraging results have been obtained in different animal models, and particularly with isolated follicles encapsulated in alginate matrices and grafted to mice. This summary is designed to guide the reader towards development of next-generation alginate scaffolds, with enhanced properties for follicle encapsulation.

  10. Effect of alginate composition on profile release and characteristics of chitosan-alginate microparticles loaded with mangosteen extract

    NASA Astrophysics Data System (ADS)

    Mulia, Kamarza; Halimah, Nur; Krisanti, Elsa

    2017-03-01

    Preparation of mangostin-loaded chitosan-alginate microparticles, chemical and physical characterization of the particles, and mangostin release profiles, are described herein. Mangostin rich fraction was obtained from Garcinia mangostana L. pericarp by extraction followed by fractionation. Mangostin-loaded chitosan-alginate microparticles were prepared by ionic gelation method using tripolyphosphate as the linking agent and various concentration of alginate. Mangostin was effectively loaded in all microparticle formulations, resulting in ˜97% encapsulation efficiencies. The loading of mangostin and the in-vitro release profiles in simulated gastrointestinal fluids were affected by the chitosan to alginate ratios used in the preparation of the microparticles. Increased alginate concentration resulted in lowered release of mangostin from microparticles immersed in simulated gastric fluid (pH 1.2) up to two hours. Low release of mangostin in acidic fluid but high release in simulated colon fluid, indicated that the chitosan-alginate microparticles are prospective carrier for extended release of active compound in gastrointestinal system.

  11. Calcium alginate dressings--I. Physico-chemical characterization and effect of sterilization.

    PubMed

    Grizzi, I; Braud, C; Vert, M

    1998-01-01

    In order to analyze the alginate components of alginate dressings and the fractions which are released when the dressing is in contact with model biological fluids, the use of various analytical methods was considered. The first step was the conversion of a calcium alginate batch to pure sodium alginate. The recovery of the latter from either insoluble or soluble mixed sodium/calcium alginates was performed by complexation of calcium ions with sodium citrate followed by ultrafiltration. Comparisons were made between sugar analysis, 1H NMR and circular dichroism (CD) data to determinate the contents in guluronic and mannuronic acids of sodium alginate chains. It was shown that CD measurements afford a rapid and nondestructive method for determination of %G when one takes the ratio theta200/theta220 into account. Fractionation of crude alginate (generally ranging from 30 to 70% G) was achieved by the triangle dissolution/precipitation method in order to increase the range of alginate in sugar composition. The various validated procedures were applied to investigate the effects of irradiation sterilization on alginate dressings. It was shown that sugar composition is retained whereas molecular weight decreased dramatically due to chain scission.

  12. Putative Alginate Assimilation Process of the Marine Bacterium Saccharophagus degradans 2-40 Based on Quantitative Proteomic Analysis.

    PubMed

    Takagi, Toshiyuki; Morisaka, Hironobu; Aburaya, Shunsuke; Tatsukami, Yohei; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2016-02-01

    Quantitative proteomic analysis was conducted to assess the assimilation processes of Saccharophagus degradans cultured with glucose, pectin, and alginate as carbon sources. A liquid chromatography-tandem mass spectrometry approach was used, employing our unique, long monolithic silica capillary column. In an attempt to select candidate proteins that correlated to alginate assimilation, the production of 23 alginate-specific proteins was identified by statistical analyses of the quantitative proteomic data. Based on the analysis, we propose that S. degradans has an alginate-specific gene cluster for efficient alginate utilization. The alginate-specific proteins of S. degradans were comprised of alginate lyases, enzymes related to carbohydrate metabolism, membrane transporters, and transcription factors. Among them, the short-chain dehydrogenase/reductase Sde_3281 annotated in the alginate-specific cluster showed 4-deoxy-L-erythro-5-hexoseulose uronic acid reductase (DehR) activity. Furthermore, we found two different genes (Sde_3280 and Sde_0939) encoding 2-keto-3-deoxy-D-gluconic acid (KDG) kinases (KdgK) that metabolize the KDG derived from alginate and pectin in S. degradans. S. degradans used Sde_3280 to phosphorylate the KDG derived from alginate and Sde_0939 to phosphorylate the KDG derived from pectin. The distinct selection of KdgKs provides an important clue toward the elucidation of how S. degradans recognizes and processes polysaccharides.

  13. Interactions of collagen molecules in the presence of N-hydroxysuccinimide activated adipic acid (NHS-AA) as a crosslinking agent.

    PubMed

    Zhang, Min; Wu, Kun; Li, Guoying

    2011-11-01

    The effect of crosslinking agent on pepsin-soluble bovine collagen solution was examined using N-hydroxysuccinimide activated adipic acid (NHS-AA) as a crosslinker. Electrophoretic patterns indicated that crosslinks formed when NHS-AA was added. A higher polarity level deduced from the changes in the fluorescence emission spectrum of pyrene in the crosslinked collagen solution indicated that the formation of well-ordered aggregates was suppressed. The random aggregation of collagens was also observed by atomic force microscopy (AFM). Furthermore, the association of collagens into fibrils was influenced by crosslinking. Self-assembly was suppressed at 37°C; however, as temperature was increased to 39°C, a small amount of NHS-AA leaded to an improvement in the ability of self-aggregation. Although more random structure was brought about by crosslinking, self-aggregation might still be promoted as temperature was increased, accompanying by the thermal stability improvement of fibrils.

  14. Influence of oligoguluronates on alginate gelation, kinetics, and polymer organization.

    PubMed

    Jørgensen, Tor Erik; Sletmoen, Marit; Draget, Kurt I; Stokke, Bjørn T

    2007-08-01

    Structural polysaccharides of the alginate family form gels in aqueous Ca2+-containing solutions by lateral association of chain segments. The effect of adding oligomers of alpha-l-guluronic acid (G blocks) to gelling solutions of alginate was investigated using rheology and atomic force microscopy (AFM). Ca-alginate gels were prepared by in situ release of Ca2+. The gel strength increased with increasing level of calcium saturation of the alginate and decreased with increasing amount of free G blocks. The presence of free G blocks also led to an increased gelation time. The gel point and fractal dimensionalities of the gels were determined based on the rheological characterization. Without added free G blocks the fractal dimension of the gels increased from df = 2.14 to df = 2.46 when increasing [Ca2+] from 10 to 20 mM. This increase was suggested to arise from an increased junction zone multiplicity induced by the increased concentration of calcium ions. In the presence of free G blocks (G block/alginate = 1/1) the fractal dimension increased from 2.14 to 2.29 at 10 mM Ca2+, whereas there was no significant change associated with addition of G blocks at 20 mM Ca2+. These observations indicate that free G blocks are involved in calcium-mediated bonds formed between guluronic acid sequences within the polymeric alginates. Thus, the added oligoguluronate competes with the alginate chains for the calcium ions. The gels and pregel situations close to the gel point were also studied using AFM. The AFM topographs indicated that in situations of low calcium saturation microgels a few hundred nanometers in diameter develop in solution. In situations of higher calcium saturation lateral association of a number of alginate chains are occurring, giving ordered fiber-like structures. These results show that G blocks can be used as modulators of gelation kinetics as well as local network structure formation and equilibrium properties in alginate gels.

  15. Alginate: properties and biomedical applications

    PubMed Central

    Lee, Kuen Yong; Mooney, David J.

    2011-01-01

    Alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications to date, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers. PMID:22125349

  16. Optimization of culturing condition and medium composition for the production of alginate lyase by a marine Vibrio sp. YKW-34

    NASA Astrophysics Data System (ADS)

    Fu, Xiaoting; Lin, Hong; Kim, Sang Moo

    2008-02-01

    Carbohydrases secreted by marine Vibrio sp. YKW-34 with strong Laminaria cell wall degrading ability were screened, and among them alginate lyase was found to be dominant. The effects of medium composition and culturing condition on the production of alginate lyase by marine Vibrio sp. YKW-34 in flask were investigated in this study. In the culture medium of marine broth, no alginate lyase was produced. The activity of the alginate lyase, after being induced, reached 5 UmL-1. The best inoculum volume and inoculum age were 10% and 12 h, respectively. The optimal temperature for alginate lyase production was 25°C. The fermentation medium was composed of 0.5% of Laminaria powder and 0.2% of KNO3 with an initial acidity of pH 8.0. Alginate could induce alginate lyase production but not as efficiently as Laminaria powder did. The addition of fucoidan, cellulose and glucose had negative effect on the alginate lyase production. Other kinds of nitrogen sources, such as yeast extract, beef extract and peptone, had positive effect on the growth of the microorganism and negative effect on alginate lyase production. In addition, the time course of alginate lyase production under the optimized condition was described. The optimal harvest time was 48 h.

  17. Nonlinear behavior of ionically and covalently cross-linked alginate hydrogels

    NASA Astrophysics Data System (ADS)

    Hashemnejad, Seyedmeysam; Zabet, Mahla; Kundu, Santanu

    2015-03-01

    Gels deform differently under applied load and the deformation behavior is related to their network structures and environmental conditions, specifically, strength and density of crosslinking, polymer concentration, applied load, and temperature. Here, we investigate the mechanical behavior of both ionically and covalent cross-linked alginate hydrogel using large amplitude oscillatory shear (LAOS) and cavitation experiments. Ionically-bonded alginate gels were obtained by using divalent calcium. Alginate volume fraction and alginate to calcium ratio were varied to obtain gels with different mechanical properties. Chemical gels were synthesized using adipic acid dihdrazide (AAD) as a cross-linker. The non-linear rheological parameters are estimated from the stress responses to elucidate the strain softening behavior of these gels. Fracture initiation and propagation mechanism during shear rheology and cavitation experiments will be presented. Our results provide a better understanding on the deformation mechanism of alginate gel under large-deformation.

  18. Superabsorbent nanocomposite (alginate-g-PAMPS/MMT): synthesis, characterization and swelling behavior.

    PubMed

    Yadav, Mithilesh; Rhee, Kyong Yop

    2012-09-01

    A superabsorbent composite (alginate-g-PAMPS/MMT) was prepared by graft copolymerization from alginate, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and Na+ montmorillonite (MMT) in an inert atmosphere. Effects of polymerization variables on water absorbency, including the content of Na+ montmorillonite, sodium alginate, N,N'-methylenebisacrylamide and AMPS, were studied. The introduced montmorillonite formed a loose and porous surface and improved the water absorbency of the alginate-g-PAMPS/MMT superabsorbent composite. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3) and anionic salt solutions (NaCl and Na2SO4) were also systematically investigated. The superabsorbent composite was further characterized using Fourier transform infrared spectroscopy (FTIR), rheology, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking alginate-g-PAMPS as a reference.

  19. Viscoelastic Behavior and Adhesion of Ionic Alginate Hydrogels

    NASA Astrophysics Data System (ADS)

    Webber, Rebecca; Shull, Kenneth

    2004-03-01

    Transient networks, polymer gels in which the physical crosslinks can be broken and recovered, have been of recent interest to the scientific community, especially due to their potential as soft, dissipative materials for biomedical applications. Alginates, naturally derived linear copolymers of mannuronic and guluronic acid residues, can form hydrogels in the presence of divalent ions. Alginate gels have been studied extensively and are useful model systems to elucidate the mechanisms behind the mechanical behavior of reversibly associating polymers. In this study, alginate hydrogels were formed by the addition of Ca ions to an aqueous solution of sodium alginate. The rheological and mechanical behavior of the hydrogels was studied using an axisymmetric probe tack apparatus with stress relaxation and cyclic movement capabilities. These hydrogels behave elastically at small strains and become viscoelastic at large strains, supporting transient network theories. During cyclic loading tests, it was found that the alginate hydrogels exhibit time-dependent adhesion. The effects of humidity, aging and ion exchange on the gel properties were also investigated.

  20. Formulation and Coating of Alginate and Alginate-Hydroxypropylcellulose Pellets Containing Ranolazine.

    PubMed

    Segale, Lorena; Mannina, Paolo; Giovannelli, Lorella; Muschert, Susanne; Pattarino, Franco

    2016-11-01

    The formulation and the coating composition of biopolymeric pellets containing ranolazine were studied to improve their technological and biopharmaceutical properties. Eudragit L100 (EU L100) and Eudragit L30 D-55-coated alginate and alginate-hydroxypropylcellulose (HPC) pellets were prepared by ionotropic gelation using 3 concentrations of HPC (0.50%, 0.65%, and 1.00% wt/wt) and applying different percentages (5%, 10%, 20%, and 30% wt/wt) of coating material. The uncoated pellets were regular in shape and had mean diameter between 1490 and 1570 μm. The rate and the entity of the swelling process were affected by the polymeric composition: increasing the HPC concentration, the structure of the pellets became more compact and slowed down the penetration of fluids. Coated alginate-HPC formulations were able to control the drug release at neutral pH: a higher quantity of HPC in the system determined a slower release of the drug. The nature of the coating polymer and the coating level applied affected the drug release in acidic environment: EU L100 gave better performance than Eudragit L30 D-55 and the best coating level was 20%. The pellets containing 0.65% of HPC and coated with 20% EU L100 represented the best formulation, able to limit the drug release in acidic environment and to control it at pH 6.8.

  1. Purification and characterization of a bifunctional alginate lyase from Pseudoalteromonas sp. SM0524.

    PubMed

    Li, Jian-Wei; Dong, Sheng; Song, Jie; Li, Chun-Bo; Chen, Xiu-Lan; Xie, Bin-Bin; Zhang, Yu-Zhong

    2011-01-21

    An alginate lyase-producing bacterial strain, Pseudoalteromonas sp. SM0524, was screened from marine rotten kelp. In an optimized condition, the production of alginate lyase from Pseudoalteromonas sp. SM0524 reached 62.6 U/mL, suggesting that strain SM0524 is a good producer of alginate lyases. The bifunctional alginate lyase aly-SJ02 secreted by strain SM0524 was purified. Aly-SJ02 had an apparent molecular mass of 32 kDa. The optimal temperature and pH of aly-SJ02 toward sodium alginate was 50 °C and 8.5, respectively. The half life period of aly-SJ02 was 41 min at 40 °C and 20 min at 50 °C. Aly-SJ02 was most stable at pH 8.0. N-terminal sequence analysis suggested that aly-SJ02 may be an alginate lyase of polysaccharide lyase family 18. Aly-SJ02 showed activities toward both polyG (α-l-guluronic acid) and polyM (β-D-mannuronic acid), indicating that it is a bifunctional alginate lyase. Aly-SJ02 had lower K(m) toward polyG than toward polyM and sodium alginate. Thin layer chromatography and ESI-MS analyses showed that aly-SJ02 mainly released dimers and trimers from polyM and alginate, and trimers and tetramers from polyG, which suggests that aly-SJ02 may be a good tool to produce dimers and trimers from alginate.

  2. Development of PVA-alginate as a matrix for enzymatic decolorization of textile dye in bioreactor system

    NASA Astrophysics Data System (ADS)

    Yanto, Dede Heri Yuli; Zahara, Syifa; Laksana, Raden Permana Budi; Anita, Sita Heris; Oktaviani, Maulida; Sari, Fahriya Puspita

    2017-01-01

    An immobilization technique using polyvinyl alcohol (PVA) crosslinked with sodium alginate as a matrix has been developed for textile dyes decolorization. Textiles use dye as an addition to the aesthetic value of the product. Dyes are generally used is a textile dye where the waste will be released directly into the waters around 2-20%. Therefore, it is important to develop an enzyme immobilization method using PVA-Alginate as a matrix. Based on the results of the study showed that the PVA-Alginate beads produced high decolorization percent compared to beads which contains only Ca-alginate alone and formula matrix is optimum at PVA 6% and alginate 1.5%. Encapsulation with boric acid at 7% showed optimum decolorization and reduction for enzyme leakage during decolorization. This study suggested that immobilization of enzymes into PVA-alginate matrix might be used as a biodecolorating agent.

  3. Alginate encapsulation parameters influence the differentiation of microencapsulated embryonic stem cell aggregates.

    PubMed

    Wilson, Jenna L; Najia, Mohamad Ali; Saeed, Rabbia; McDevitt, Todd C

    2014-03-01

    Pluripotent embryonic stem cells (ESCs) have tremendous potential as tools for regenerative medicine and drug discovery, yet the lack of processes to manufacture viable and homogenous cell populations of sufficient numbers limits the clinical translation of current and future cell therapies. Microencapsulation of ESCs within microbeads can shield cells from hydrodynamic shear forces found in bioreactor environments while allowing for sufficient diffusion of nutrients and oxygen through the encapsulation material. Despite initial studies examining alginate microbeads as a platform for stem cell expansion and directed differentiation, the impact of alginate encapsulation parameters on stem cell phenotype has not been thoroughly investigated. Therefore, the objective of this study was to systematically examine the effects of varying alginate compositions on microencapsulated ESC expansion and phenotype. Pre-formed aggregates of murine ESCs were encapsulated in alginate microbeads composed of a high or low ratio of guluronic to mannuronic acid residues (High G and High M, respectively), with and without a poly-L-lysine (PLL) coating, thereby providing four distinct alginate bead compositions for analysis. Encapsulation in all alginate compositions was found to delay differentiation, with encapsulation within High G alginate yielding the least differentiated cell population. The addition of a PLL coating to the High G alginate prevented cell escape from beads for up to 14 days. Furthermore, encapsulation within High M alginate promoted differentiation toward a primitive endoderm phenotype. Taken together, the findings of this study suggest that distinct ESC expansion capacities and differentiation trajectories emerge depending on the alginate composition employed, indicating that encapsulation material physical properties can be used to control stem cell fate.

  4. Effet de l'acide ascorbique sur la détermination du plomb dans des matrices végétales par ETA-AAS

    NASA Astrophysics Data System (ADS)

    Hoenig, Michel; Van Hoeyweghen, Paul

    Sulphuric acid used in wet oxidation of plant material and the matrix elements are responsible for a strong suppression of lead absorption signals and for the poor reproducibility of the measurements with ETA-AAS. Addition of ascorbic acid to samples (2% m/V) provides an enhancement in sensitivity by more than 200% and leads to acceptable values of the relative error. The results obtained with the 283.3 nm line are better than those obtained with the 217.0 nm line.

  5. Effect of insulin-transferrin-selenium (ITS) and l-ascorbic acid (AA) during in vitro maturation on in vitro bovine embryo development.

    PubMed

    Guimarães, A L S; Pereira, S A; Diógenes, M N; Dode, M A N

    2016-12-01

    The aim of this study was to evaluate the effect of adding a combination of insulin, transferrin and selenium (ITS) and l-ascorbic acid (AA) during in vitro maturation (IVM) and in vitro culture (IVC) on in vitro embryo production. To verify the effect of the supplements, cleavage and blastocyst rates, embryo size and total cell number were performed. Embryonic development data, embryo size categorization and kinetics of maturation were analyzed by chi-squared test, while the total cell number was analyzed by a Kruskal-Wallis test (P < 0.05). When ITS was present during IVM, IVC or the entire culture, all treatments had a cleavage and blastocyst rates and embryo quality, similar to those of the control group (P < 0.05). Supplementation of IVM medium with ITS and AA for 12 h or 24 h showed that the last 12 h increased embryo production (51.6%; n = 220) on D7 compared with the control (39.5%; n = 213). However, no improvement was observed in blastocyst rate when less competent oocytes, obtained from 1-3 mm follicles, were exposed to ITS + AA for the last 12 h of IVM, with a blastocyst rate of 14.9% (n = 47) compared with 61.0% (n = 141) in the control group. The results suggest that the addition of ITS alone did not affect embryo production; however, when combined with AA in the last 12 h of maturation, there was improvement in the quantity and quality of embryos produced. Furthermore, the use of ITS and AA during IVM did not improve the competence of oocytes obtained from small follicles.

  6. Synthesis and Characterization of Sodium Alginate Conjugate and Study of Effect of Conjugation on Drug Release from Matrix Tablet

    PubMed Central

    Satheeshababu, B. K.; Mohamed, I.

    2015-01-01

    The aim of the present research work to study the effect of conjugation of the polymer on drug release from the matrix tablets. Sodium alginate L-cysteine conjugate was achieved by covalent attachment of thiol group of L-cysteine with the primary amino group of sodium alginate through the amide bonds formed by primary amino groups of the sodium alginate and the carboxylic acid group of L-cysteine. The synthesised sodium alginate L-cysteine conjugate was characterised by determining of charring point, Fourier transmission-infrared and differential scanning calorimetric analysis. To study the effect of conjugation on drug release pattern, the matrix tablets were prepared using various proportions of sodium alginate and sodium alginate L-cysteine conjugate along with atorvastatin calcium as model drug. The wet granulation technique was adopted and prepared matrix tablets were evaluated for various physical parameters. The in vitro drug release study results suggested that tablet formulated in combination of sodium alginate and sodium alginate L-cysteine conjugate S4 showed 100% after 8 h drug release whereas formulated with only sodium alginate S0 released 40% in 8 h. PMID:26798173

  7. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  8. 21 CFR 582.7133 - Ammonium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammonium alginate. 582.7133 Section 582.7133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Ammonium alginate. (a) Product. Ammonium alginate. (b) Conditions of use. This substance is...

  9. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  10. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  11. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  12. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  13. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  14. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  15. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  16. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  17. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  18. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  19. Swelling and aspirin release study: cross-linked pH-sensitive vinyl acetate-co-acrylic acid (VAC-co-AA) hydrogels.

    PubMed

    Ranjha, Nazar Mohammad; Mudassir, Jahanzeb

    2008-05-01

    The objective of this work was to develop new pH-sensitive hydrogels to deliver gastric mucosal irritating drugs to the lower part of the gastrointestinal tract. For this purpose, cross-linked vinyl acetate-co-acrylic acid (VAC-co-AA) hydrogels were synthesized by using N, N, methylene bisacrylamide (MBAAm) as a cross-linking agent. Different ratios of 90:10, 70:30, 50:50, 30:70, and 10:90 of VAC-co-AA were synthesized. All of the compositions were cross-linked using 0.15, 0.30, 0.45, and 0.60 mol percent MBAAm. Swelling and aspirin release were studied for 8 hour period. The drug release data were fitted into various kinetic models like the zero-order, first-order, Higuchi, and Peppas. Hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. In addition to the above, these hydrogels were loaded with 2%, 8% and 14% w/v aspirin solutions, keeping the monomeric composition and degree of cross-linking constant. In conclusion, it can be said that aspirin can be successfully incorporated into cross-linked VAC/AA hydrogels and its swelling and drug release can be modulated by changing the mole fraction of the acid component in the gels.

  20. Preparation and swelling properties of pH-sensitive composite hydrogel beads based on chitosan-g-poly (acrylic acid)/vermiculite and sodium alginate for diclofenac controlled release.

    PubMed

    Wang, Qin; Xie, Xiaoling; Zhang, Xiaowei; Zhang, Junping; Wang, Aiqin

    2010-04-01

    A series of pH-sensitive composite hydrogel beads, chitosan-g-poly (acrylic acid)/vermiculite/sodium alginate (CTS-g-PAA/VMT/SA), was prepared using CTS-g-PAA/VMT composite and SA by Ca(2+) as the crosslinking agent. The structure and morphologies of the developed composite hydrogel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling properties and pH-sensitivity of the beads were investigated. In addition, the drug loading and controlled release behaviors of the beads were also evaluated using diclofenac sodium (DS) as the model drug in stimulated gastric fluids (pH 2.1) and intestinal fluids (pH 6.8). The results indicate that the composite hydrogel beads showed good pH-sensitivity. The release rate of the drug from the composite hydrogel beads is remarkably slowed down, which indicated that incorporating VMT into the composite hydrogel beads can improve the burst release effect of the drug.

  1. Efficient functionalization of alginate biomaterials.

    PubMed

    Dalheim, Marianne Ø; Vanacker, Julie; Najmi, Maryam A; Aachmann, Finn L; Strand, Berit L; Christensen, Bjørn E

    2016-02-01

    Peptide coupled alginates obtained by chemical functionalization of alginates are commonly used as scaffold materials for cells in regenerative medicine and tissue engineering. We here present an alternative to the commonly used carbodiimide chemistry, using partial periodate oxidation followed by reductive amination. High and precise degrees of substitution were obtained with high reproducibility, and without formation of by-products. A protocol was established using l-Tyrosine methyl ester as a model compound and the non-toxic pic-BH3 as the reducing agent. DOSY was used to indirectly verify covalent binding and the structure of the product was further elucidated using NMR spectroscopy. The coupling efficiency was to some extent dependent on alginate composition, being most efficient on mannuronan. Three different bioactive peptide sequences (GRGDYP, GRGDSP and KHIFSDDSSE) were coupled to 8% periodate oxidized alginate resulting in degrees of substitution between 3.9 and 6.9%. Cell adhesion studies of mouse myoblasts (C2C12) and human dental stem cells (RP89) to gels containing various amounts of GRGDSP coupled alginate demonstrated the bioactivity of the material where RP89 cells needed higher peptide concentrations to adhere.

  2. Nonlinear elasticity of alginate gels

    NASA Astrophysics Data System (ADS)

    Hashemnejad, Seyed Meysam; Kundu, Santanu

    Alginate is a naturally occurring anionic polysaccharide extracted from brown algae. Because of biocompatibility, low toxicity, and simple gelation process, alginate gels are used in biomedical and food applications. Here, we report the rheological behavior of ionically crosslinked alginate gels, which are obtained by in situ gelation of alginates with calcium salts, in between two parallel plates of a rheometer. Strain stiffening behavior was captured using large amplitude oscillatory shear (LAOS) experiments. In addition, negative normal stress was observed for these gels, which has not been reported earlier for any polysaccharide networks. The magnitude of negative normal stress increases with applied strain and can exceed that of the shear stress at large strain. Rheological results fitted with a constitutive model that considers both stretching and bending of chains indicate that nonlinearity is likely related to the stretching of the chains between the crosslink junctions. The results provide an improved understanding of the deformation mechanism of ionically crosslinked alginate gel and the results will be important in developing synthetic extracellular matrix (ECM) from these materials.

  3. Heparin-like properties of sulfated alginates with defined sequences and sulfation degrees.

    PubMed

    Arlov, Øystein; Aachmann, Finn Lillelund; Sundan, Anders; Espevik, Terje; Skjåk-Bræk, Gudmund

    2014-07-14

    Sulfated glycosaminoglycans have a vast range of protein interactions relevant to the development of new biomaterials and pharmaceuticals, but their characterization and application is complicated mainly due to a high structural variability and the relative difficulty to isolate large quantities of structurally homogeneous samples. Functional and versatile analogues of heparin/heparan sulfate can potentially be created from sulfated alginates, which offer structure customizability through targeted enzymatic epimerization and precise tuning of the sulfation degree. Alginates are linear polysaccharides consisting of β-D-mannuronic acid (M) and α-L-guluronic acid (G), derived from brown algae and certain bacteria. The M/G ratio and distribution of blocks are critical parameters for the physical properties of alginates and can be modified in vitro using mannuronic-C5-epimerases to introduce sequence patterns not found in nature. Alginates with homogeneous sequences (poly-M, poly-MG, and poly-G) and similar molecular weights were chemically sulfated and structurally characterized by the use of NMR and elemental analysis. These sulfated alginates were shown to bind and displace HGF from the surface of myeloma cells in a manner similar to heparin. We observed dependence on the sulfation degree (DS) as well as variation in efficacy based on the alginate monosaccharide sequence, relating to relative flexibility and charge density in the polysaccharide chains. Co-incubation with human plasma showed complement compatibility of the alginates and lowering of soluble terminal complement complex levels by sulfated alginates. The sulfated polyalternating (poly-MG) alginate proved to be the most reproducible in terms of precise sulfation degrees and showed the greatest relative degree of complement inhibition and HGF interaction, maintaining high activity at low DS values.

  4. The effect of omeprazole pre-treatment on rafts formed by reflux suppressant tablets containing alginate.

    PubMed

    Dettmar, P W; Little, S L; Baxter, T

    2005-01-01

    Alginate-based reflux suppressant preparations provide symptom relief by forming a physical barrier on top of the stomach contents in the form of a neutral floating gel or raft. This study investigated whether reduced acidity in the stomach brought about by omeprazole pre-treatment affected the formation and gastric residence time of alginate rafts. It was a balanced, cross-over study in 12 healthy non-patient volunteers following a single dose of two indium-111-labelled alginate tablets in the presence or absence of 3 days' pre-treatment with omeprazole. Raft formation and gastric residence, in the presence of a technetium-99m-labelled meal, were assessed by gamma scintigraphy for 3 h after alginate tablet administration. The relative raft-forming ability of alginate tablets after omeprazole compared with alginate tablets alone was 0.950 with 95% confidence intervals of 0.882 and 1.018. Pre-treatment and co-administration with omeprazole has no significant effect on the raft-forming ability of alginate tablets.

  5. Magnetic Pycnoporus sanguineus-loaded alginate composite beads for removing dye from aqueous solutions.

    PubMed

    Yang, Chih-Hui; Shih, Ming-Cheng; Chiu, Han-Chen; Huang, Keng-Shiang

    2014-06-18

    Dye pollution in wastewater is a severe environmental problem because treating water containing dyes using conventional physical, chemical, and biological treatments is difficult. A conventional process is used to adsorb dyes and filter wastewater. Magnetic filtration is an emerging technology. In this study, magnetic Pycnoporus sanguineus-loaded alginate composite beads were employed to remove a dye solution. A white rot fungus, P. sanguineus, immobilized in alginate beads were used as a biosorbent to remove the dye solution. An alginate polymer could protect P. sanguineus in acidic environments. Superparamagnetic nanomaterials, iron oxide nanoparticles, were combined with alginate gels to form magnetic alginate composites. The magnetic guidability of alginate composites and biocompatibility of iron oxide nanoparticles facilitated the magnetic filtration and separation processes. The fungus cells were immobilized in loaded alginate composites to study the influence of the initial dye concentration and pH on the biosorption capacity. The composite beads could be removed easily post-adsorption by using a magnetic filtration process. When the amount of composite beads was varied, the results of kinetic studies of malachite green adsorption by immobilized cells of P. sanguineus fitted well with the pseudo-second-order model. The results indicated that the magnetic composite beads effectively adsorbed the dye solution from wastewater and were environmentally friendly.

  6. In vitro fermentation of alginate and its derivatives by human gut microbiota.

    PubMed

    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. 3D Cell Culture in Alginate Hydrogels

    PubMed Central

    Andersen, Therese; Auk-Emblem, Pia; Dornish, Michael

    2015-01-01

    This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell–matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue. PMID:27600217

  8. RGD-peptide modified alginate by a chemoenzymatic strategy for tissue engineering applications.

    PubMed

    Sandvig, Ioanna; Karstensen, Kristin; Rokstad, Anne Mari; Aachmann, Finn Lillelund; Formo, Kjetil; Sandvig, Axel; Skjåk-Bræk, Gudmund; Strand, Berit Løkensgard

    2015-03-01

    One of the main challenges in tissue engineering and regenerative medicine is the ability to maintain optimal cell function and survival post-transplantation. Biomaterials such as alginates are commonly used for immunoisolation, while they may also provide structural support to the cell transplants by mimicking the extracellular matrix. In this study, arginine-glycine-aspartate (RGD)-peptide-coupled alginates of tailored composition were produced by adopting a unique chemoenzymatic strategy for substituting the nongelling mannuronic acid on the alginate. Alginates with and without RGD were produced with high and low content of G. Using carbodiimide chemistry 0.1-0.2% of the sugar units were substituted by peptide. Furthermore, the characterization by (1)H-nuclear magnetic resonance (NMR) revealed by-products from the coupling reaction that partly could be removed by coal filtration. Olfactory ensheathing cells (OECs) and myoblasts were grown in two-dimensional (2D) and 3D cultures of RGD-peptide modified or unmodified alginates obtained by the chemoenzymatically strategy and compared to native alginate. Both OECs and myoblasts adhered to the RGD-peptide modified alginates in 2D cultures, forming bipolar protrusions. OEC encapsulation resulted in cell survival for up to 9 days, thus demonstrating the potential for short-term 3D culture. Myoblasts showed long-term survival in 3D cultures, that is, up to 41 days post encapsulation. The RGD modifications did not result in marked changes in cell viability in 3D cultures. We demonstrate herein a unique technique for tailoring peptide substituted alginates with a precise and flexible composition, conserving the gel forming properties relevant for the use of alginate in tissue engineering.

  9. Survivability of probiotics encapsulated in alginate gel microbeads using a novel impinging aerosols method.

    PubMed

    Sohail, Asma; Turner, Mark S; Coombes, Allan; Bostrom, Thor; Bhandari, Bhesh

    2011-01-31

    Encapsulation of probiotic bacteria in cross-linked alginate beads is of major interest for improving the survivability in harsh acid and bile environment and also in food matrices. Alginate micro beads (10-40 μm) containing the probiotics Lactobacillus rhamnosus GG and Lactobacillus acidophilus NCFM were produced by a novel technique based on dual aerosols of alginate solution and CaCl(2) cross linking solution. Extruded macro beads (approximately 2mm diameter) produced by the conventional method and micro beads produced by novel aerosols technique offered comparable protection to L. rhamnosus in high acid and bile environment. Chitosan coating of micro beads resulted in a significant increase in survival time of L. rhamnosus from 40 to 120 min in acid condition and the reduction in cell numbers was confined to 0.94 log over this time. Alginate macro beads are more effective than micro beads in protecting L. acidophilus against high acid and bile. Chitosan coating of micro beads resulted in similar protection to L. acidophilus in macro beads in acid and extended the survival time from 90 to at least 120 min. Viability of this organism in micro beads was 3.5 log after 120 min. The continuous processing capability and scale-up potential of the dual aerosol technique offers potential for an efficient encapsulation of probiotics in very small alginate micro beads below sensorial detection limits while still being able to confer effective protection in acid and bile environment.

  10. EB1 levels are elevated in ascorbic Acid (AA)-stimulated osteoblasts and mediate cell-cell adhesion-induced osteoblast differentiation.

    PubMed

    Pustylnik, Sofia; Fiorino, Cara; Nabavi, Noushin; Zappitelli, Tanya; da Silva, Rosa; Aubin, Jane E; Harrison, Rene E

    2013-07-26

    Osteoblasts are differentiated mesenchymal cells that function as the major bone-producing cells of the body. Differentiation cues including ascorbic acid (AA) stimulation provoke intracellular changes in osteoblasts leading to the synthesis of the organic portion of the bone, which includes collagen type I α1, proteoglycans, and matrix proteins, such as osteocalcin. During our microarray analysis of AA-stimulated osteoblasts, we observed a significant up-regulation of the microtubule (MT) plus-end binding protein, EB1, compared with undifferentiated osteoblasts. EB1 knockdown significantly impaired AA-induced osteoblast differentiation, as detected by reduced expression of osteoblast differentiation marker genes. Intracellular examination of AA-stimulated osteoblasts treated with EB1 siRNA revealed a reduction in MT stability with a concomitant loss of β-catenin distribution at the cell cortex and within the nucleus. Diminished β-catenin levels in EB1 siRNA-treated osteoblasts paralleled an increase in phospho-β-catenin and active glycogen synthase kinase 3β, a kinase known to target β-catenin to the proteasome. EB1 siRNA treatment also reduced the expression of the β-catenin gene targets, cyclin D1 and Runx2. Live immunofluorescent imaging of differentiated osteoblasts revealed a cortical association of EB1-mcherry with β-catenin-GFP. Immunoprecipitation analysis confirmed an interaction between EB1 and β-catenin. We also determined that cell-cell contacts and cortically associated EB1/β-catenin interactions are necessary for osteoblast differentiation. Finally, using functional blocking antibodies, we identified E-cadherin as a major contributor to the cell-cell contact-induced osteoblast differentiation.

  11. Alginate Lyase Exhibits Catalysis-Independent Biofilm Dispersion and Antibiotic Synergy

    PubMed Central

    Lamppa, John W.

    2013-01-01

    More than 2 decades of study support the hypothesis that alginate lyases are promising therapeutic candidates for treating mucoid Pseudomonas aeruginosa infections. In particular, the enzymes' ability to degrade alginate, a key component of mucoid biofilm matrix, has been the presumed mechanism by which they disrupt biofilms and enhance antibiotic efficacy. The systematic studies reported here show that, in an in vitro model, alginate lyase dispersion of P. aeruginosa biofilms and enzyme synergy with tobramycin are completely decoupled from catalytic activity. In fact, equivalent antibiofilm effects can be achieved with bovine serum albumin or simple amino acids. These results provide new insights into potential mechanisms of alginate lyase therapeutic activity, and they should motivate a careful reexamination of the fundamental assumptions underlying interest in enzymatic biofilm dispersion. PMID:23070175

  12. Characterization and Immunological Evaluation of Low-Molecular- Weight Alginate Derivatives.

    PubMed

    Xu, Xu; Bi, Decheng; Wan, Min

    2016-01-01

    Alginate is a naturally occurring acidic linear polysaccharide obtained from marine brown seaweed. Low molecular weight structurally diverse derivatives and oligosaccharides derived from alginate have shown various tremendous biological and pharmacological activities. It has been demonstrated that immuno-inflammation is involved in many prevalent human diseases, such as cancer, severe infection and neurodegeneration. Given the activities of marine natural products in the regulation of immune responses, increasing efforts are being made toward the development of lowmolecular- weight natural compounds that aid in the prevention and treatment of immune- and inflammatory-related diseases. In this review, we describe the development of chemical modification and molecular depolymerization methods that modify the physicochemical and biological characteristics of alginate. Additionally, current progress in research on immuno-inflammatory, anti-neurodegenerative and anti-tumor activities of alginate derivatives is highlighted.

  13. Preparation of carbon nanotube-alginate nanocomposite gel for tissue engineering.

    PubMed

    Kawaguchi, Minoru; Fukushima, Tadao; Hayakawa, Toru; Nakashima, Naotoshi; Inoue, Yusuke; Takeda, Shoji; Okamura, Kazuhiko; Taniguchi, Kunihisa

    2006-12-01

    A novel scaffold material based on an alginate hydrogel which contained carbon nanotubes (CNTs) was prepared, and its mechanical property and biocompatibility evaluated. Soluble CNTs were prepared with acid treatment and dispersed in sodium alginate solution as a cross-linker. After which, the mechanical property (elastic deformation), saline sorption, histological reaction, and cell viability of the resultant nanocomposite gel (CNT-Alg gel) were evaluated. The CNT-Alg gel showed faster gelling and higher mechanical strength than the conventional alginate gel. Saline sorption amount of freeze-dried CNT-Alg gel was equal to that of the alginate gel. In terms of histological evaluation and cell viability assay, CNT-Alg gel exhibited a mild inflammatory response and non-cytotoxicity. These results thus suggested that CNT-Alg gel could be useful as a scaffold material in tissue engineering with the sidewalls of CNTs acting as active sites for chemical functionalization.

  14. Bile salt-reinforced alginate-chitosan beads.

    PubMed

    Takka, Sevgi; Cali, Aybige Gürel

    2012-01-01

    A polymeric delayed release protein delivery system was investigated with albumin as the model drug. The polysaccharide chitosan was reacted with sodium alginate in the presence of calcium chloride to form beads with a polyelectrolyte. In this study, attempts were made to extend albumin release in the phosphate buffer at pH 6.8 from the alginate-chitosan beads by reinforcing the matrix with bile salts. Sodium taurocholate was able to prevent albumin release at pH 1.2, protecting the protein from the acidic environment and extending the total albumin release at pH 6.8. This effect was explained by an interaction between the permanent negatively charged sulfonic acid of sodium taurocholate with the amino groups of chitosan. Mild formulation conditions, high bovine serum albumin (BSA) entrapment efficiency, and resistance to gastrointestinal release seem to be synergic and promising factors toward the development of an oral protein delivery form.

  15. Purification, characterization, and immunological cross-reactivity of alginates produced by mucoid Pseudomonas aeruginosa from patients with cystic fibrosis.

    PubMed

    Pedersen, S S; Espersen, F; Høiby, N; Shand, G H

    1989-04-01

    Alginates from nine mucoid Pseudomonas aeruginosa isolates from patients with cystic fibrosis were purified by repeated ethanol precipitation, nuclease digestion, anion-exchange chromatography, dialysis, and lyophilization. Uronic acid constituted 72% of the dry weight when mannuronolactone was used as the internal standard in the carbazole-borate assay for uronic acids. The average degree of acetylation was 16%, and the ratio of mannuronic acid to gluluronic acid was 4.7. No homopolymeric blocks of guluronic acid were found when analyzed by nuclear magnetic resonance spectroscopy. Contaminating proteins were denatured by heating, and during purification the content of protein relative to alginate fell from 566 to 0.9%. The content of lipopolysaccharide was 0.012%. No immunological or biological activity was attributable to the protein or lipopolysaccharide content as estimated by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and a neutrophil chemotaxis assay. Rabbits were hyperimmunized with P. aeruginosa alginates and alginate from the seaweed Laminaria hyperborea, and an ELISA that detected alginate-specific antibodies was developed. Antibodies to P. aeruginosa alginate were detected by ELISA in 1:4,000 dilutions of serum from patients with cystic fibrosis with chronic P. aeruginosa lung infection. The serological cross-reactions between serum from the nine patients with cystic fibrosis and the corresponding P. aeruginosa alginates were investigated and showed considerable heterogeneity. This finding indicates that P. aeruginosa alginate from more than one P. aeruginosa strain should be used in serological tests. There was no serological cross-reactivity between P. aeruginosa and Laminaria hyperborea alginate in either rabbits or patients with cystic fibrosis.

  16. Gingival Mesenchymal Stem Cell (GMSC) Delivery System Based on RGD-Coupled Alginate Hydrogel with Antimicrobial Properties: A Novel Treatment Modality for Peri-Implantitis

    PubMed Central

    Diniz, Ivana M. A.; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H.; Moshaverinia, Maryam; Chee, Daniel; Marques, Márcia M.; Shi, Songtao; Moshaverinia, Alireza

    2015-01-01

    Purpose Peri-implantitis is one of the most common inflammatory complications in dental implantology. Similar to periodontitis, in peri-implantitis, destructive inflammatory changes take place in the tissues surrounding a dental implant. Bacterial flora at the failing implant sites resemble the pathogens in periodontal disease and consist of Gram-negative anaerobic bacteria including Aggregatibacter actinomycetemcomitans (Aa). Here we demonstrate the effectiveness of a silver lactate (SL)-containing RGD-coupled alginate hydrogel scaffold as a promising stem cell delivery vehicle with antimicrobial properties. Materials and Methods Gingival mesenchymal stem cells (GMSCs) or human bone marrow mesenchymal stem cells (hBMMSCs) were encapsulated in SL-loaded alginate hydrogel microspheres. Stem cell viability, proliferation, and osteo-differentiation capacity were analyzed. Results Our results showed that SL exhibited antimicrobial properties against Aa in a dose-dependent manner, with 0.50 mg/ml showing the greatest antimicrobial properties while still maintaining cell viability. At this concentration, SL-containing alginate hydrogel was able to inhibit Aa on the surface of Ti discs and significantly reduce the bacterial load in Aa suspensions. Silver ions were effectively released from the SL-loaded alginate microspheres for up to 2 weeks. Osteogenic differentiation of GMSCs and hBMMSCs encapsulated in the SL-loaded alginate microspheres were confirmed by the intense mineral matrix deposition and high expression of osteogenesis-related genes. Conclusion Taken together, our findings confirm that GMSCs encapsulated in RGD-modified alginate hydrogel containing SL show promise for bone tissue engineering with antimicrobial properties against Aa bacteria in vitro. PMID:26216081

  17. Alginate as a protease inhibitor in vitro and in a model gut system; selective inhibition of pepsin but not trypsin.

    PubMed

    Chater, Peter Ian; Wilcox, Mathew D; Brownlee, Iain A; Pearson, Jeffrey P

    2015-10-20

    Alginates are widely used in the food and medical industries, including as a Gastro-Oesophagul Reflux treatment. This work investigates the inhibitory effects of alginate on the reflux aggressors trypsin and pepsin and the role of alginate-substrate binding, pH and alginate structure on inhibition. Alginates were shown to reduce pepsin activity by up to 53.9% (±9.5SD) in vitro. Strong positive correlation between alginate mannuronate residue frequency and levels of pepsin inhibition was observed. Limited inhibition of trypsin was shown. Viscometric observations of pH dependent interactions between alginate and protein suggest a mechanism whereby pH dependent ionic interactions reduce substrate availability to enzyme at acidic pH. To understand how dietary protein digestion is affected by alginate, proteolytic digestion was investigated in an in vitro model of the upper digestive tract. Significant inhibition of proteolysis was shown in the gastric phase of digestion, but not the small intestinal phase.

  18. Preparation of calcium alginate microgel beads in an electrodispersion reactor using an internal source of calcium carbonate nanoparticles.

    PubMed

    Zhao, Yinyan; Carvajal, M Teresa; Won, You-Yeon; Harris, Michael T

    2007-12-04

    An electrodispersion reactor has been used to prepare calcium alginate (Ca-alginate) microgel beads in this study. In the electrodispersion reactor, pulsed electric fields are utilized to atomize aqueous mixtures of sodium alginate and CaCO3 nanoparticles (dispersed phase) from a nozzle into an immiscible, insulating second liquid (continuous phase) containing a soluble organic acid. This technique combines the features of the electrohydrodynamic force driven emulsion processes and externally triggered gelations in microreactors (the droplets) ultimately to yield soft gel beads. The average particle size of the Ca-alginate gels generated by this method changed from 412 +/- 90 to 10 +/- 3 microm as the applied peak voltage was increased. A diagram depicting structural information for the Ca-alginate was constructed as a function of the concentrations of sodium alginate and CaCO3 nanoparticles. From this diagram, a critical concentration of sodium alginate required for sol-gel transformation was observed. The characteristic highly porous structure of Ca-alginate particles made by this technique appears suitable for microencapsulation applications. Finally, time scale analysis was performed for the electrodispersion processes that include reactions in the microreactor droplets to provide guidelines for the future employment of this technique. This electrodispersion reactor can be used potentially in the formation of many reaction-based microencapsulation systems.

  19. Enzyme-catalyzed phase transition of alginate gels and gelatin-alginate interpenetrated networks.

    PubMed

    Doumèche, Bastien; Picard, Julien; Larreta-Garde, Véronique

    2007-11-01

    The enzyme-catalyzed gel-sol transition of calcium-alginate obtained by internal gelling strategy with the help of an entrapped alginate lyase is described. We show that alginate molecules and enzyme-produced oligoalginates shorten the gel time of physical gelatin gels (5% and 1.5%), probably due to local protein concentration increase. Interpenetrated networks composed of calcium-alginate and of gelatin were obtained only if elongation of gelatin helices inside a pre-existing calcium-alginate network could occur and only for low gelatin concentration (1.5%). The physical gelatin network is almost reversible inside the alginate one. Both networks can be obtained in the presence of alginate lyase, but gel-sol transition of calcium-alginate cannot be obtained in the presence of gelatin.

  20. 40 CFR Appendix A to Subpart Aa of... - Applicability of General Provisions (40 CFR Part 63, Subpart A) to Subpart AA

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (40 CFR Part 63, Subpart A) to Subpart AA A Appendix A to Subpart AA of Part 63 Protection of... Hazardous Air Pollutants From Phosphoric Acid Manufacturing Plants Pt. 63, Subpt. AA, App. A Appendix A to Subpart AA of Part 63—Applicability of General Provisions (40 CFR Part 63, Subpart A) to Subpart AA 40...

  1. 40 CFR Appendix A to Subpart Aa of... - Applicability of General Provisions (40 CFR Part 63, Subpart A) to Subpart AA

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (40 CFR Part 63, Subpart A) to Subpart AA A Appendix A to Subpart AA of Part 63 Protection of... Hazardous Air Pollutants From Phosphoric Acid Manufacturing Plants Pt. 63, Subpt. AA, App. A Appendix A to Subpart AA of Part 63—Applicability of General Provisions (40 CFR Part 63, Subpart A) to Subpart AA 40...

  2. Cyclic AMP regulation of arachidonic acid (AA) release and phospholipid metabolism in human monocytes: modulation by intracellular calcium

    SciTech Connect

    Hoffstein, S.T.; Manzi, R.M.; Godfrey, R.W.

    1986-05-01

    Stimulation of inflammatory cells by specific ligands results in activation of phospholipase(s) and production of oxygenation products of AA. The authors have employed (/sup 3/H)AA labeled monocytes to examine the involvement of cAMP in regulating phospholipase activity as measured by percent of incorporated (/sup 3/H)AA released and TLC analysis of (/sup 3/H)AA cellular lipids. Maximum release of radiolabel (31 +/- 5%) occurred upon challenge with the calcium ionophore A23187/sup -/ (10..mu..M), while FMLP (1..mu..M) yielded 15 +/- 1% and untreated cells 8 +/- 1%. Pretreatment of monocytes with isobutyl methyl xanthine/sup -/(IBMX) or dibutyrl cyclic AMP (d-cAMP) inhibited FMLP stimulated release with IC/sub 50/'s of 2.5 x 10/sup -5/M and 8 x 10/sup -5/M respectively. Exposure of monocytes to maximal levels of IBMX (5 x 10/sup -4/M) or d-cAMP (10/sup -3/M) also reduced release from controls by 40%, while A23187 induced release was uneffected by either. Examination of (/sup 3/H) AA labeled phospholipids showed that phosphatidylcholine (PC) and phosphatidylinositol were the major pools labeled and that stimulation by FMLP or A23187 appeared to deplete the PC pool exclusively. Prior exposure to IBMX or d-cAMP inhibited the loss from the PC pool only in untreated or FMLP stimulated cells. The data suggests that a phospholipase A/sub 2/ activity, directly primarily towards PC, is regulated by cAMP possibly by inhibiting receptor mediated increases in intracellular calcium levels.

  3. Non-Invasive Evaluation of Alginate/Poly-L-lysine/Alginate Microcapsules by Magnetic Resonance Microscopy

    PubMed Central

    Constantinidis, Ioannis; Grant, Samuel C.; Celper, Susanne; Gauffin-Holmberg, Isabel; Agering, Kristina; Oca-Cossio, Jose A.; Bui, Jonathan D.; Flint, Jeremy; Hamaty, Christine; Simpson, Nicholas E.; Blackband, Stephen J.

    2007-01-01

    In this report, we present data to demonstrate the utility of 1H MR microscopy to noninvasively examine alginate/poly-L-lysine/alginate (APA) microcapsules. Specifically, high-resolution images were used to visualize and quantify the poly-L-lysine (PLL) layer, and monitor temporal changes in the alginate gel microstructure during a month long in vitro culture. The thickness of the alginate/PLL layer was quantified to be 40.6±6.2 μm regardless of the alginate composition used to generate the beads or the time of alginate/PLL interaction (2, 6, or 20 minutes). However, there was a notable difference in the contrast of the PLL layer that depended upon the guluronic content of the alginate and the alginate/PLL interaction time. The T2 relaxation time and the apparent diffusion coefficient (ADC) of the alginate matrix were measured periodically throughout the month long culture period. Alginate beads generated with a high guluronic content alginate demonstrated a temporal decrease in T2 over the duration of the experiment, while ADC was unaffected. This decrease in T2 is attributed to a reorganization of the alginate microstructure due to periodic media exchanges that mimicked a regular feeding regiment for cultured cells. In beads coated with a PLL layer, this temporal decrease in T2 was less pronounced suggesting that the PLL layer helped maintain the integrity of the initial alginate microstructure. Conversely, alginate beads generated with a high mannuronic content alginate (with or without a PLL layer) did not display temporal changes in either T2 or ADC. This observation suggests that the microstructure of high mannuronic content alginate beads is less susceptible to culture conditions. PMID:17239948

  4. FLX Pyrosequencing Analysis of the Effects of the Brown-Algal Fermentable Polysaccharides Alginate and Laminaran on Rat Cecal Microbiotas

    PubMed Central

    An, Choa; Yazaki, Takahiro; Takahashi, Hajime; Kimura, Bon

    2013-01-01

    Edible brown algae are used as major food material in Far East Asian countries, particularly in South Korea and Japan. They contain fermentable dietary fibers, alginic acid (uronic acid polymer) and laminaran (β-1,3-glucan), that are fermented into organic acids by intestinal bacteria. To clarify the effect of edible algae on the intestinal environment, the cecal microbiotas of rats fed diets containing no dietary fiber (control) or 2% (wt/wt) sodium alginate or laminaran for 2 weeks were analyzed using FLX amplicon pyrosequencing with bar-coded primers targeting the bacterial 16S rRNA gene. The most abundant phylum in all groups was Firmicutes. Specifically, Allobaculum was dominant in all diet groups. In addition, Bacteroides capillosus (37.1%) was abundant in the alginate group, while Clostridium ramosum (3.14%) and Parabacteroides distasonis (1.36%) were only detected in the laminaran group. Furthermore, rats fed alginate showed simplified microbiota phylotypes compared with others. With respect to cecal chemical compounds, laminaran increased cecal organic acid levels, particularly propionic acid. Alginate increased total cecal organic acids. Cecal putrefactive compounds, such as indole, H2S, and phenol, were decreased by both alginate and laminaran. These results indicate that edible brown algae can alter the intestinal environment, with fermentation by intestinal microbiota. PMID:23183985

  5. Controlled release of carbofuran from an alginate-bentonite formulation: water release kinetics and soil mobility.

    PubMed

    Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E; Martinez-López, F; Flores-Céspedes, F

    2000-03-01

    The insecticide-nematicide carbofuran was incorporated in alginate-based granules to obtain controlled-release (CR) properties. The basic formulation [sodium alginate (1.61%)-carbofuran (0. 59%)-water] was modified by addition of sorbents. The effect on carbofuran release rate, caused by the incorporation of natural and acid-treated bentonite (0.5 and 1.0 M H(2)SO(4)) in alginate formulation, was studied by immersion of the granules in water under shaking. The time taken for 50% of the active ingredient to be released into water, t(50), was longer for those formulations containing natural bentonite (6.1 h) or acid-treated bentonite (9.0 and 11.7 h for 0.5 and 1.0 M H(2)SO(4) treatments, respectively) than for the preparation without bentonite (4.7 h). It appears from the results that the release of carbofuran from the various formulations is controlled by a diffusion mechanism according to the n values obtained, which were close to 0.5 in all cases. The mobility of carbofuran from alginate-based CR formulations was investigated by using soil columns packed with a clay soil (53% clay and 0.08% organic matter). Two alginate-based CR formulations containing natural bentonite or acid-treated bentonite (0.5 M H(2)SO(4)) were compared to technical grade carbofuran. The use of alginate-based CR formulations resulted in a reduction of the leached amount of carbofuran compared with the total amount of pesticide leached using the technical product (50 and 75% for CR granules containing natural and acid-treated bentonite, respectively). Alginate-bentonite CR formulations might be efficient systems for reducing carbofuran leaching in clay soils, which would reduce the risk of groundwater pollution.

  6. Engineering alginate for intervertebral disc repair.

    PubMed

    Bron, Johannes L; Vonk, Lucienne A; Smit, Theodoor H; Koenderink, Gijsje H

    2011-10-01

    Alginate is frequently studied as a scaffold for intervertebral disc (IVD) repair, since it closely mimics mechanical and cell-adhesive properties of the nucleus pulposus (NP) of the IVD. The aim of this study was to assess the relation between alginate concentration and scaffold stiffness and find preparation conditions where the viscoelastic behaviour mimics that of the NP. In addition, we measured the effect of variations in scaffold stiffness on the expression of extracellular matrix molecules specific to the NP (proteoglycans and collagen) by native NP cells. We prepared sample discs of different concentrations of alginate (1%-6%) by two different methods, diffusion and in situ gelation. The stiffness increased with increasing alginate concentration, while the loss tangent (dissipative behaviour) remained constant. The diffusion samples were ten-fold stiffer than samples prepared by in situ gelation. Sample discs prepared from 2% alginate by diffusion closely matched the stiffness and loss tangent of the NP. The stiffness of all samples declined upon prolonged incubation in medium, especially for samples prepared by diffusion. The biosynthetic phenotype of native cells isolated from NPs was preserved in alginate matrices up to 4 weeks of culturing. Gene expression levels of extracellular matrix components were insensitive to alginate concentration and corresponding matrix stiffness, likely due to the poor adhesiveness of the cells to alginate. In conclusion, alginate can mimic the viscoelastic properties of the NP and preserve the biosynthetic phenotype of NP cells but certain limitations like long-term stability still have to be addressed.

  7. Engineering alginate as bioink for bioprinting

    PubMed Central

    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

    2015-01-01

    Recent advances in 3D printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been extensively utilized as bioinks for 3D 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, we prepared a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations to develop a bioink platform that can be applied to a multitude of tissue engineering applications. We 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 structure integrity of the lattice structures (except the highly degradable one) after 8 days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  8. Engineering alginate as bioink for bioprinting.

    PubMed

    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.

  9. Identification of enzymes responsible for extracellular alginate depolymerization and alginate metabolism in Vibrio algivorus.

    PubMed

    Doi, Hidetaka; Tokura, Yuriko; Mori, Yukiko; Mori, Kenichi; Asakura, Yoko; Usuda, Yoshihiro; Fukuda, Hiroo; Chinen, Akito

    2017-02-01

    Alginate is a marine non-food-competing polysaccharide that has potential applications in biorefinery. Owing to its large size (molecular weight >300,000 Da), alginate cannot pass through the bacterial cell membrane. Therefore, bacteria that utilize alginate are presumed to have an enzyme that degrades extracellular alginate. Recently, Vibrio algivorus sp. SA2(T) was identified as a novel alginate-decomposing and alginate-utilizing species. However, little is known about the mechanism of alginate degradation and metabolism in this species. To address this issue, we screened the V. algivorus genomic DNA library for genes encoding polysaccharide-decomposing enzymes using a novel double-layer plate screening method and identified alyB as a candidate. Most identified alginate-decomposing enzymes (i.e., alginate lyases) must be concentrated and purified before extracellular alginate depolymerization. AlyB of V. algivorus heterologously expressed in Escherichia coli depolymerized extracellular alginate without requiring concentration or purification. We found seven homologues in the V. algivorus genome (alyB, alyD, oalA, oalB, oalC, dehR, and toaA) that are thought to encode enzymes responsible for alginate transport and metabolism. Introducing these genes into E. coli enabled the cells to assimilate soluble alginate depolymerized by V. algivorus AlyB as the sole carbon source. The alginate was bioconverted into L-lysine (43.3 mg/l) in E. coli strain AJIK01. These findings demonstrate a simple and novel screening method for identifying polysaccharide-degrading enzymes in bacteria and provide a simple alginate biocatalyst and fermentation system with potential applications in industrial biorefinery.

  10. Production of a calcium silicate cement material from alginate impression material.

    PubMed

    Washizawa, Norimasa; Narusawa, Hideaki; Tamaki, Yukimichi; Miyazaki, Takashi

    2012-01-01

    The purpose of this study was to synthesize biomaterials from daily dental waste. Since alginate impression material contains silica and calcium salts, we aimed to synthesize calcium silicate cement from alginate impression material. Gypsum-based investment material was also investigated as control. X-ray diffraction analyses revealed that although firing the set gypsum-based and modified investment materials at 1,200°C produced calcium silicates, firing the set alginate impression material did not. However, we succeeded when firing the set blend of pre-fired set alginate impression material and gypsum at 1,200°C. SEM observations of the powder revealed that the featured porous structures of diatomite as an alginate impression material component appeared useful for synthesizing calcium silicates. Experimentally fabricated calcium silicate powder was successfully mixed with phosphoric acid solution and set by depositing the brushite. Therefore, we conclude that the production of calcium silicate cement material is possible from waste alginate impression material.

  11. Effects of purified alginate sponge on the regeneration of chondrocytes: in vitro and in vivo.

    PubMed

    Song, Jeong Eun; Kim, A Ram; Lee, Cheon Jung; Tripathy, Nirmalya; Yoon, Kun Ho; Lee, Dongwon; Khang, Gilson

    2015-01-01

    Regeneration science has been studied using tissue engineering techniques due to the self-renewal difficulties of damaged or degenerated cartilage. A scaffold with biodegradability and biocompatibility features plays a key role in developing cartilage tissue similar to human biological materials. Herein, we have fabricated three-dimensional sponge using purified alginate for the regeneration of chondrocytes cells and formation of cartilage. We demonstrated that the alginate purification can effectively minimize inflammatory reaction through reducing the content of mannuronic acid causing immune rejection. Cartilage regeneration research was performed using three-dimensional non-purified and purified alginate sponges synthesized by modified Korbutt method. In vitro cell viability and specific gene expression in the cartilage cells were investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and reverse transcriptase-polymerase chain reaction (RT-PCR) after seeding chondrocytes on the as-fabricated sponges. Specific extracellular matrix (ECM) of chondrocytes, sGAG, and the content of collagen were also measured. Histological staining was carried out after purified alginate sponge seeded with chondrocytes and was implanted in subcutaneous nude mouse followed by extraction. Compared to the non-purified ones, the purified alginate sponges showed positive effects on maintaining affinities and phenotype of chondrocytes. From these results, it can be suggested that the purified alginate sponges provide a promising platform for cartilage regeneration.

  12. Alginate cryogel based glucose biosensor

    NASA Astrophysics Data System (ADS)

    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.

  13. Biocomposite cellulose-alginate films: promising packaging materials.

    PubMed

    Sirviö, Juho Antti; Kolehmainen, Aleksi; Liimatainen, Henrikki; Niinimäki, Jouko; Hormi, Osmo E O

    2014-05-15

    Biocomposite films based on cellulose and alginate were produced using unmodified birch pulp, microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC) and birch pulp derivate, nanofibrillated anionic dicarboxylic acid cellulose (DCC), having widths of fibres ranging from 19.0 μm to 25 nm as cellulose fibre materials. Ionically cross-linked biocomposites were produced using Ca(2+) cross-linking. Addition of micro- and nanocelluloses as a reinforcement increased the mechanical properties of the alginate films remarkably, e.g. addition of 15% of NFC increased a tensile strength of the film from 70.02 to 97.97 MPa. After ionic cross-linking, the tensile strength of the film containing 10% of DCC was increased from 69.63 to 125.31 MPa. The biocomposite films showed excellent grease barrier properties and reduced water vapour permeability (WVP) after the addition of cellulose fibres, except when unmodified birch pulp was used.

  14. Red fluorescent protein DsRed: parametrization of its chromophore as an amino acid residue for computer modeling in the OPLS-AA force field.

    PubMed

    Dmitrienko, D V; Vrzheshch, E P; Drutsa, V L; Vrzheshch, P V

    2006-10-01

    Topology of the neutral form of the DsRed fluorescent protein chromophore as a residue of [(4-cis)-2-[(1-cis)-4-amino-4-oxobutanimidoyl]-4-(4-hydroxybenzylidene)-5-oxo-4,5-dihydro-1H-imidazol-1-yl]acetic acid was calculated with OPLS-AA force field. Use of this topology and molecular dynamics simulation allows calculating the parameters of proteins that contain such residue in their polypeptide chains. The chromophore parameters were obtained by ab initio (RHF/6-31G**) quantum chemical calculations applying density functional theory (B3LYP). Using this chromophore, we have calculated the molecular dynamics trajectory of tetrameric fluorescent protein DsRed in solution at 300 K (4 nsec). Correctness of the chromophore parametrization was revealed by comparison of quantitative characteristics of the chromophore structure obtained from the molecular dynamic simulations of DsRed protein with the quantitative characteristics of the chromophore based on the crystallographic X-ray data of fluorescent protein DsRed (PDB ID: 1ZGO, 1G7K, and 1GGX), and also with the quantitative characteristics of the chromophore obtained by quantum chemical calculations. Inclusion of the neutral form of DsRed protein chromophore topology into the OPLS-AA force field yielded the extended force field OPLS-AA/DsRed. This force field can be used for molecular dynamics calculations of proteins containing the DsRed chromophore. The parameter set presented in this study can be applied for similar extension in any other force fields.

  15. Bacterial community structure and predicted alginate metabolic pathway in an alginate-degrading bacterial consortium.

    PubMed

    Kita, Akihisa; Miura, Toyokazu; Kawata, Satoshi; Yamaguchi, Takeshi; Okamura, Yoshiko; Aki, Tsunehiro; Matsumura, Yukihiko; Tajima, Takahisa; Kato, Junichi; Nishio, Naomichi; Nakashimada, Yutaka

    2016-03-01

    Methane fermentation is one of the effective approaches for utilization of brown algae; however, this process is limited by the microbial capability to degrade alginate, a main polysaccharide found in these algae. Despite its potential, little is known about anaerobic microbial degradation of alginate. Here we constructed a bacterial consortium able to anaerobically degrade alginate. Taxonomic classification of 16S rRNA gene, based on high-throughput sequencing data, revealed that this consortium included two dominant strains, designated HUA-1 and HUA-2; these strains were related to Clostridiaceae bacterium SK082 (99%) and Dysgonomonas capnocytophagoides (95%), respectively. Alginate lyase activity and metagenomic analyses, based on high-throughput sequencing data, revealed that this bacterial consortium possessed putative genes related to a predicted alginate metabolic pathway. However, HUA-1 and 2 did not grow on agar medium with alginate by using roll-tube method, suggesting the existence of bacterial interactions like symbiosis for anaerobic alginate degradation.

  16. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level.

    PubMed

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein; Ertesvåg, Helga

    2015-12-11

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface.

  17. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level

    PubMed Central

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein

    2015-01-01

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface. PMID:26655760

  18. Doped copolymer of polyanthranilic acid and o-aminophenol (AA-co-OAP): Synthesis, spectral characterization and the use of the doped copolymer as precursor of α-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Hosny, Nasser Mohammed; Nowesser, Nourhan; Al-Hussaini, A. S.; Zoromba, Mohamed Shafick

    2016-02-01

    The copolymer of anthranilic acid and o-aminophenol (AA-co-OAP) was synthesized and characterized by IR, UV-Vis. and thermal analyses (TGA). Linear chain mode was suggested for the pure (AA-co-OAP). The effect of inclusion of MnCl2, CoCl2, NiCl2, CuCl2 and FeCl3 on the spectral, thermal and optical properties of AA-co-OAP has been studied. Octahedral stereochemistry was suggested for Fe, Mn and Ni doped AA-co-OAP, while tetrahedral and square-planar geometries were suggested for Co and Cu doped AA-co-OAP, respectively. Fe doped AA-co-OAP has been used as a precursor for α-Fe2O3 nanoparticles by thermal decomposition route at 800 °C. The obtained hematite has been characterized by XRD and TEM. The average size of the prepared nanoparticles was estimated as 34 nm. The optical band gap of the synthesized hematite nanoparticles was measured and compared with the bulk.

  19. Scaling law and microstructure of alginate hydrogel.

    PubMed

    Liu, Sijun; Li, Huijun; Tang, Bijun; Bi, Shuguang; Li, Lin

    2016-01-01

    The gelation of alginate in aqueous solution was studied as a function of Ca(2+) concentration. At each given concentration of alginate, a critical gel concentration [Formula: see text] , was successfully determined for the first time using the Winter-Chambon criterion. The critical gel concentration [Formula: see text] was found to increase linearly with alginate concentration. At the same time, the critical relaxation exponent n decreased and the critical gel strength Sg increased linearly with alginate concentration. An improved egg-box model was proposed to describe the change in gel junction and gel network. In the stable gel state, the plateau modulus Ge of alginate gel depended on Ca(2+) concentration according to a power-law scaling, Ge=kɛ(1.5), where ɛ is the relative distance of a gelling variable (Ca(2+) concentration in this case) from the gel point ( [Formula: see text] ). The FESEM images verified the microstructure of alginate gel in which alginate chains associated into fibrils in the presence of Ca(2+) ions. The fibrillar diameter and network density increased with increasing Ca(2+) ion concentration while alginate concentration had a weak influence on fibrillar diameter.

  20. Chiroptical characterization of homopolymeric block fractions in alginates.

    PubMed

    Martínez-Gómez, Fabián; Mansilla, Andrés; Matsuhiro, Betty; Matulewicz, María C; Troncoso-Valenzuela, Marcos A

    2016-08-01

    Homopolymannuronic and homopolyguluronic fractions were obtained by partial hydrolysis of the alkaline extracts from the brown seaweeds Ascoseira mirabilis, Desmarestia menziessi, Desmarestia ligulata and Durvillaea sp. collected in southern Chile. Full characterization of the fractions was achieved by FT-IR and NMR spectroscopy. Total hydrolysis with 90% formic acid of the homopolymeric fractions allowed the preparation of mannuronic and guluronic acids. Both monomers and homopolymeric fractions as neutral salts were studied by CD and ORD. Chiroptical spectra were similar in shape and sign to those previously published in the literature, and permitted to assign D configuration to mannuronic acid and L configuration to guluronic acid in alginic acids. Specific optical rotation values at the sodium D light for the homopolymannuronic (∼-100°) and homopolyguluronic (∼-110°) acid fractions were obtained. These high negative values are proposed for the assignment of the absolute configuration of monomers in homopolymeric fractions.

  1. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions.

  2. Rheological characterization and turbidity of riboflavin-photosensitized changes in alginate/GDL systems.

    PubMed

    Baldursdóttir, Stefanía G; Kjøniksen, Anna-Lena

    2005-04-01

    Riboflavin (RF) in combination with light, in the wavelength range of 310-800 nm, is used to induce degradation of alginic acid gels. Light irradiation of alginate solutions in the presence of RF under aerobic conditions causes scission of the polymer chains. In the development process of a new drug delivery system, RF photosensitized degradation of alginic acid gels is studied by monitoring changes in the turbidity and rheological parameters of alginate/glucono-delta-lactone (GDL) systems with different concentrations of GDL. Addition of GDL induces gel formation of the samples by gradually lowering the pH-value of the system. The turbidity is measured and the cloud point determined. The turbidity starts to increase after shorter times with enhanced concentration of GDL. Enhanced viscoelasticity is detected with increasing GDL concentration in the post-gel regime, but small differences are detected at the gel point. The incipient gel is 'soft' and has an open structure independent on the GDL concentration. In the post-gel regime solid-like behavior is observed, this is more distinct for the systems with high GDL concentrations. The effect of photosensitized RF on alginate/GDL systems decreases with increasing amount of GDL in the system. The same trend is detected whether the systems are irradiated in the pre-gel or in the post-gel regime.

  3. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    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.

  4. Improved production of reducing sugars from rice straw using crude cellulase activated with Fe₃O₄/alginate nanocomposite.

    PubMed

    Srivastava, Neha; Singh, Jay; Ramteke, Pramod W; Mishra, P K; Srivastava, Manish

    2015-05-01

    Effect of Fe3O4 nanoparticles (NPs) and Fe3O4/Alginate nanocomposites (NCs) have been investigated on production and thermostability of crude cellulase enzyme system obtained by newly isolated thermotolerant Aspergillus fumigatus AA001. Fe3O4 NPs and Fe3O4/Alginate NCs have been synthesized by co-precipitation method and characterized through various techniques. In presence of Fe3O4 NPs and Fe3O4/Alginate NCs, filter paper activity of crude cellulase was increased about 35% and 40%, respectively in 72 h as compared to control. Fe3O4/Alginate NCs treated crude enzyme was thermally stable up to 8h at 70°C and retained 56% of its relative activity whereas; control samples could retain only 19%. Further, the hydrolysis of 1.0% alkali treated rice straw using Fe3O4/Alginate NCs treated cellulase gave much higher sugar productivity than control at optimal condition. These findings may be utilized in the area of biofuels and biowaste management.

  5. Calcium Alginate and Calcium Alginate-Chitosan Beads Containing Celecoxib Solubilized in a Self-Emulsifying Phase

    PubMed Central

    Segale, Lorena; Giovannelli, Lorella; Mannina, Paolo; Pattarino, Franco

    2016-01-01

    In this work alginate and alginate-chitosan beads containing celecoxib solubilized into a self-emulsifying phase were developed in order to obtain a drug delivery system for oral administration, able to delay the drug release in acidic environment and to promote it in the intestinal compartment. The rationale of this work was linked to the desire to improve celecoxib therapeutic effectiveness reducing its gastric adverse effects and to favor its use in the prophylaxis of colon cancer and as adjuvant in the therapy of familial polyposis. The systems were prepared by ionotropic gelation using needles with different diameters (400 and 600 μm). Morphology, particle size, swelling behavior, and in vitro drug release performance of the beads in aqueous media with different pH were investigated. The experimental results demonstrated that the presence of chitosan in the formulation caused an increase of the mechanical resistance of the bead structure and, as a consequence, a limitation of the bead swelling ability and a decrease of the drug release rate at neutral pH. Alginate-chitosan beads could be a good tool to guarantee a celecoxib colon delivery. PMID:27127680

  6. Rating AAs.

    ERIC Educational Resources Information Center

    Carter, Susan J.

    2001-01-01

    Why alternative investments? In a word: performance. Many higher education endowment and foundation managers are making increasing commitments to alternative investments, or AAs, in order to obtain higher returns and broader diversification for their investment portfolios than public securities instruments can usually provide. Learn how to handle…

  7. Membrane-anchored MucR mediates nitrate-dependent regulation of alginate production in Pseudomonas aeruginosa.

    PubMed

    Wang, Yajie; Hay, Iain D; Rehman, Zahid U; Rehm, Bernd H A

    2015-09-01

    Alginates exhibit unique material properties suitable for medical and industrial applications. However, if produced by Pseudomonas aeruginosa, it is an important virulence factor in infection of cystic fibrosis patients. The alginate biosynthesis machinery is activated by c-di-GMP imparted by the inner membrane protein, MucR. Here, it was shown that MucR impairs alginate production in response to nitrate in P. aeruginosa. Subsequent site-specific mutagenesis of MucR revealed that the second MHYT sensor motif (MHYT II, amino acids 121-124) of MucR sensor domain was involved in nitrate sensing. We also showed that both c-di-GMP synthesizing and degrading active sites of MucR were important for alginate production. Although nitrate and deletion of MucR impaired alginate promoter activity and global c-di-GMP levels, alginate yields were not directly correlated with alginate promoter activity or c-di-GMP levels, suggesting that nitrate and MucR modulate alginate production at a post-translational level through a localized pool of c-di-GMP. Nitrate increased pel promoter activity in the mucR mutant while in the same mutant the psl promoter activity was independent of nitrate. Nitrate and deletion of mucR did not impact on swarming motility but impaired attachment to solid surfaces. Nitrate and deletion of mucR promoted the formation of biofilms with increased thickness, cell density, and survival. Overall, this study provided insight into the functional role of MucR with respect to nitrate-mediated regulation of alginate biosynthesis.

  8. Oxidative potential of ambient water-soluble PM2.5 measured by Dithiothreitol (DTT) and Ascorbic Acid (AA) assays in the southeastern United States: contrasts in sources and health associations

    NASA Astrophysics Data System (ADS)

    Fang, T.; Verma, V.; Bates, J. T.; Abrams, J.; Klein, M.; Strickland, M. J.; Sarnat, S. E.; Chang, H. H.; Mulholland, J. A.; Tolbert, P. E.; Russell, A. G.; Weber, R. J.

    2015-11-01

    The ability of certain components of particulate matter to induce oxidative stress through catalytic generation of reactive oxygen species (ROS) in vivo may be one mechanism accounting for observed linkages between ambient aerosols and adverse health outcomes. A variety of assays have been used to measure this so-called aerosol oxidative potential. We developed a semi-automated system to quantify oxidative potential of filter aqueous extracts utilizing the dithiothreitol (DTT) assay and have recently developed a similar semi-automated system using the ascorbic acid (AA) assay. Approximately 500 PM2.5 filter samples collected in contrasting locations in the southeastern US were analyzed using both assays. We found that water-soluble DTT activity on a per air volume basis was more spatially uniform than water-soluble AA activity. DTT activity was higher in winter than in summer/fall, whereas AA activity was higher in summer/fall compared to winter, with highest levels near highly trafficked highways. DTT activity was correlated with organic and metal species, whereas AA activity was correlated with water-soluble metals (especially water-soluble Cu, r=0.70-0.91 at most sites). Source apportionment models, Positive Matrix Factorization (PMF) and a Chemical Mass Balance Method with ensemble-averaged source impact profiles (CMB-E), suggest a strong contribution from secondary processes (e.g., organic aerosol oxidation or metal mobilization by formation of an aqueous particle with secondary acids) and traffic emissions to both DTT and AA activities in urban Atlanta. Biomass burning was a large source for DTT activity, but insignificant for AA. DTT activity was well correlated with PM2.5 mass (r=0.49-0.86 across sites/seasons), while AA activity did not co-vary strongly with mass. A linear model was developed to estimate DTT and AA activities for the central Atlanta Jefferson Street site, based on the CMB-E sources that are statistically significant with positive

  9. Oxidative potential of ambient water-soluble PM2.5 in the southeastern United States: contrasts in sources and health associations between ascorbic acid (AA) and dithiothreitol (DTT) assays

    NASA Astrophysics Data System (ADS)

    Fang, Ting; Verma, Vishal; Bates, Josephine T.; Abrams, Joseph; Klein, Mitchel; Strickland, Matthew J.; Sarnat, Stefanie E.; Chang, Howard H.; Mulholland, James A.; Tolbert, Paige E.; Russell, Armistead G.; Weber, Rodney J.

    2016-03-01

    The ability of certain components of particulate matter to induce oxidative stress through the generation of reactive oxygen species (ROS) in vivo may be one mechanism accounting for observed linkages between ambient aerosols and adverse health outcomes. A variety of assays have been used to measure this so-called aerosol oxidative potential. We developed a semi-automated system to quantify oxidative potential of filter aqueous extracts utilizing the dithiothreitol (DTT) assay and report here the development of a similar semi-automated system for the ascorbic acid (AA) assay. Approximately 500 PM2.5 filter samples collected in contrasting locations in the southeastern US were analyzed for a host of aerosol species, along with AA and DTT activities. We present a detailed contrast in findings from these two assays. Water-soluble AA activity was higher in summer and fall than in winter, with highest levels near heavily trafficked highways, whereas DTT activity was higher in winter compared to summer and fall and more spatially homogeneous. AA activity was nearly exclusively correlated with water-soluble Cu (r = 0.70-0.94 at most sites), whereas DTT activity was correlated with organic and metal species. Source apportionment models, positive matrix factorization (PMF) and a chemical mass balance method with ensemble-averaged source impact profiles (CMB-E), suggest a strong contribution from traffic emissions and secondary processes (e.g., organic aerosol oxidation or metals mobilization by secondary acids) to both AA and DTT activities in urban Atlanta. In contrast, biomass burning was a large source for DTT activity, but insignificant for AA. AA activity was not correlated with PM2.5 mass, while DTT activity co-varied strongly with mass (r = 0.49-0.86 across sites and seasons). Various linear models were developed to estimate AA and DTT activities for the central Atlanta Jefferson Street site, based on the CMB-E sources. The models were then used to estimate daily

  10. New treatments using alginate in order to reduce the calcification of bovine bioprosthetic heart valve tissue.

    PubMed

    Shanthi, C; Rao, K P

    1997-01-01

    Calcification limits the functional lifetime of cardiac valve substitutes fabricated from glutaraldehyde preserved bovine pericardium. Host factors, mainly younger age, and implant factors, mainly glutaraldehyde cross-linking, are implicated in the calcification process. Glutaraldehyde cross-linking is believed to activate the potential sites in the tissues for biocalcification. In the present work, we investigated the possibility of using alginate azide (AA) instead of glutaraldehyde for the preservation of pericardial tissues in order to enhance the durability of bioprosthetic heart valves. Grafting with poly(GMA-BA) copolymer to the alginate azide cross-linked pericardial (AACPC) tissue was carried out to obtain better stability, strength, and anticalcification properties. The strength property and thermal stability of the AA cross-linked tissues were studied. Calcification studies in rat subdermal models reveal that AA cross-linking reduces the calcification to negligible levels. After 30 days implantation, the calcium content was found to be 10.4 +/- 1.2 and 6.1 +/- 0.3 micrograms mg-1 for untreated AACPC and polymer grafted AACPC, respectively, compared to a value of 100 +/- 1.2 micrograms mg-1 calcium recorded for control glutaraldehyde cross-linked pericardial (GCPC) tissues.

  11. Microencapsulation of a synbiotic into PLGA/alginate multiparticulate gels.

    PubMed

    Cook, Michael T; Tzortzis, George; Charalampopoulos, Dimitris; Khutoryanskiy, Vitaliy V

    2014-05-15

    Probiotic bacteria have gained popularity as a defence against disorders of the bowel. However, the acid sensitivity of these cells results in a loss of viability during gastric passage and, consequently, a loss of efficacy. Probiotic treatment can be supplemented using 'prebiotics', which are carbohydrates fermented specifically by probiotic cells in the body. This combination of probiotic and prebiotic is termed a 'synbiotic'. Within this article a multiparticulate dosage form has been developed, consisting of poly(d,l-lactic-co-glycolic acid) (PLGA) microcapsules containing prebiotic Bimuno™ incorporated into an alginate-chitosan matrix containing probiotic Bifidobacterium breve. The aim of this multiparticulate was that, in vivo, the probiotic would be protected against gastric acid and the release of the prebiotic would occur in the distal colon. After microscopic investigation, this synbiotic multiparticulate was shown to control the release of the prebiotic during in vitro gastrointestinal transit, with the release of galacto-oligosaccharides (GOS) initially occurred over 6h, but with a triphasic release pattern giving further release over 288 h. Encapsulation of B. breve in multiparticulates resulted in a survival of 8.0 ± 0.3 logCFU/mL cells in acid, an improvement over alginate-chitosan microencapsulation of 1.4 logCFU/mL. This was attributed to increased hydrophobicity by the incorporation of PLGA particles.

  12. A simple approach for morphology tailoring of alginate particles by manipulation ionic nature of polyurethanes.

    PubMed

    Daemi, Hamed; Barikani, Mehdi; Barmar, Mohammad

    2014-05-01

    A number of different ionic aqueous polyurethane dispersions (PUDs) were synthesized based on NCO-terminated prepolymers. Two different anionic and cationic polyurethane samples were synthesized using dimethylol propionic acid and N-methyldiethanolamine emulsifiers, respectively. Then, proper amounts of PUDs and sodium alginate were mixed to obtain a number of aqueous polyurethane dispersions-sodium alginate (PUD/SA) elastomers. The chemical structure, thermal, morphological, thermo-mechanical and mechanical properties, and hydrophilicity content of the prepared samples were studied by FTIR, EDX, DSC, TGA, SEM, DMTA, tensile testing and contact angle techniques. The cationic polyurethanes and their blends with sodium alginate showed excellent miscibility and highly stretchable properties, while the samples containing anionic polyurethanes and alginate illustrated a poor compatibility and no significant miscibility. The morphology of alginate particles shifted from nanoparticles to microparticles by changing the nature of PUDs from cationic to anionic types. The final cationic elastomers not only showed better mechanical properties but also were formulated easier than anionic samples.

  13. Preparation, characterization, and sensing behavior of polydiacetylene liposomes embedded in alginate fibers.

    PubMed

    Kauffman, Jennifer S; Ellerbrock, Brett M; Stevens, Kathryn A; Brown, Philip J; Pennington, William T; Hanks, Timothy W

    2009-06-01

    Polydiacetylene (PDA)-doped calcium alginate fibers were created by the solution blending of polymerized 10,12-pentacosadiynoic acid liposomes with sodium alginate in water prior to extrusion. The liposomes maintained their blue color during wet spinning and drying of the fibers but changed to red with exposure to specific external stimuli (heat, solvent, and chemical). In the latter case, the color change only occurred when the fibers were sufficiently permeable for the reacting species to reach the interior. A parameter termed the "Raman response" (RR) has been developed to quantify the amount of PDA liposomes in each of two critical conformations within the fibers. The RR attributes a quantitative measure of PDA response to individual stimuli. This method provides advantages over the commonly used "colorimetric response" in systems where sample limitations and chromophore activity make UV-vis spectroscopic measurements difficult or inaccurate. PDA liposomes are shown to effectively add a versatile sensing component to alginate fibers.

  14. Microfluidics-assisted generation of stimuli-responsive hydrogels based on alginates incorporated with thermo-responsive and amphiphilic polymers as novel biomaterials.

    PubMed

    Karakasyan, C; Mathos, J; Lack, S; Davy, J; Marquis, M; Renard, D

    2015-11-01

    We used a droplet-based microfluidics technique to produce monodisperse responsive alginate-block-polyetheramine copolymer microgels. The polyetheramine group (PEA), corresponding to a propylene oxide /ethylene oxide ratio (PO/EO) of 29/6 (Jeffamine(®) M2005), was condensed, via the amine link, to alginates with various mannuronic/guluronic acids ratios and using two alginate:jeffamine mass ratios. The size of the grafted-alginate microgels varied from 60 to 80 μm depending on the type of alginate used and the degree of substitution. The droplet-based microfluidics technique offered exquisite control of both the dimension and physical chemical properties of the grafted-alginate microgels. These microgels were therefore comparable to isolated grafted-alginate chains in retaining both their amphiphilic and thermo-sensitive properties. Amphiphilicity was demonstrated at the oil-water interface where grafted-alginate microgels were found to decrease interfacial tension by ∼ 50%. The thermo-sensitivity of microgels was clearly demonstrated and a 10 to 20% reduction in size between was evidenced on increasing the temperature above the lower critical solution temperature (TLCST) of Jeffamine. In addition, the reversibility of thermo-sensitivity was demonstrated by studying the oil-water affinity of microgels with temperature after Congo red labeling. Finally, droplet-based microfluidics was found to be a good and promising tool for generating responsive biobased hydrogels for drug delivery applications and potential new colloidal stabilizers for dispersed systems such as Pickering emulsions.

  15. Alginate increases water stability whilst maintaining diet digestibility in farmed saltwater crocodiles ().

    PubMed

    Francis, Magdalene; Morel, Patrick C H; Wilkinson, Brian H P; Wester, Timothy J

    2017-02-01

    Saltwater crocodile () farming in Papua New Guinea is an emerging industry that supplies high-quality skins to the fashion industry. Crocodiles are semiaquatic and fed high-quality feed made from extrudated animal byproducts (i.e., forced through a die at low pressure but not heat treated); however, it disintegrates on contact with water, and this leads to low utilization. Alginate is used extensively in food and pharmaceutical processes because it quickly forms a gel at room temperature; however, its effects on nutrient availability are equivocal, and its utility in crocodile diets is unknown. Extrudated chicken byproduct-based crocodile diets were formulated (as-fed) with and without 1.7 and 3.3% Na alginate with either CaCl or CaCO to cross-link. After immersion in water at 30°C for 24 h, feed retained on a 0.5-mm screen was measured to determine DM retention (DMR). Regardless of inclusion level, alginate addition resulted in a 13-fold increase in DMR ( < 0.05) when CaCO was used as a Ca source; however, CaCl use resulted in a much lower DMR. In a digestibility trial, 10 juvenile crocodiles (2.2 to 2.4 yr of age; 1.2 to 1.9 kg BW) were chosen from farm-raised stocks and fed extrudated chicken byproduct-based diets with and without 1.5% Na alginate and 1.9% CaCO. Animals fed 2% BW for 12 d and with excreta collected the last 5 d were slaughtered and had digesta sampled from the ileum. There were no differences in apparent ileal digestibilities of any AA, N (65.0 vs. 55.8%, SE = 12.2%), and OM (46.8 vs. 39.6%, SE = 12.8%) between diets with and without alginate, respectively. Total-tract digestibilities of OM (69.8 vs. 39.2%, SE = 9.1%) and energy (72.2 vs. 44.4%, SE = 8.3%), however, were greater in alginate-containing diets ( < 0.05). Our study showed that alginate addition to crocodile feed improved its stability in water and did not impair nutrient digestion. Application of these findings should greatly decrease feed wastage, which ultimately will benefit

  16. Lead removal in rats using calcium alginate.

    PubMed

    Savchenko, Olga V; Sgrebneva, Marina N; Kiselev, Vladimir I; Khotimchenko, Yuri S

    2015-01-01

    Lead (Pb) exposure, even at low levels, causes a variety of health problems. The aims of this study were to investigate the tissue distribution of lead in the bodies of rats, to evaluate lead removal from the internal organs and bones using calcium alginate in doses of 500, 200 and 100 mg/kg per day for 28 days and to assess the impact of calcium alginate on the level of essential elements. Lead (Pb), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn) levels in the blood, hearts, kidneys, livers and femurs of the experimental animals were measured using mass spectrometry with inductively coupled plasma. The results revealed that lead acetate exposure increased the levels of Pb in the blood and organs of the animals and significantly reduced contents of Ca, Mn, Fe, Cu and Zn. Treatment with calcium alginate in dose 500 mg/kg contributed to significant decreases in the amount of lead in the kidney, heart and bones of animals and a slight increase in the content of essential elements in the liver, kidneys and heart, although these changes were not significant. Decreasing of lead was not significant in the internal organs, bones and blood of animals treated with calcium alginate 200 and 100 mg/kg. Consequently, calcium alginate dose of 500 mg/kg more efficiently removes lead accumulated in the body. Calcium alginate does not have negative effect on level of essential elements quite the contrary; reducing the levels of lead, calcium alginate helps normalize imbalances of Ca, Mn, Fe, Cu and Zn. The results of this study suggest that calcium alginate may potentially be useful for the treatment and prevention of heavy metal intoxications.

  17. Characterization of an encapsulation device for the production of monodisperse alginate beads for cell immobilization.

    PubMed

    Serp, D; Cantana, E; Heinzen, C; Von Stockar, U; Marison, I W

    2000-10-05

    An encapsulation device, designed on the basis of the laminar jet break-up technique, is characterized for cell immobilization with different types of alginate. The principle of operation of the completely sterilizable encapsulator, together with techniques for the continuous production of beads from 250 microm to 1 mm in diameter, with a size distribution below 5%, at a flow rate of 1-15 mL/min, is described. A modification of the device, to incorporate an electrostatic potential between the alginate droplets and an internal electrode, results in enhanced monodispersity with no adverse effects on cell viability. The maximum cell loading capacity of the beads strongly depends on the nozzle diameter as well as the cells used. For the yeast Phaffia rhodozyma, it is possible to generate 700 microm alginate beads with an initial cell concentration of 1 x 10(8) cells/mL of alginate whereas only 1 x 10(6) cells/ml could be entrapped within 400 microm beads. The alginate beads have been characterized with respect to mechanical resistance and size distribution immediately after production and as a function of storage conditions. The beads remain stable in the presence of acetic acid, hydrochloric acid, water, basic water, and sodium ions. The latter stability applies when the ratio of sodium: calcium ions is less than 1/5. Complexing agents such as sodium citrate result in the rapid solubilization of the beads due to calcium removal. The presence of cells does not affect the mechanical resistance of the beads. Finally, the mechanical resistance of alginate beads can be doubled by treatment with 5-10 kDa chitosan, resulting in reduced leaching of cells.

  18. A Comparison between Ultraviolet Disinfection and Copper Alginate Beads within a Vortex Bioreactor for the Deactivation of Bacteria in Simulated Waste Streams with High Levels of Colour, Humic Acid and Suspended Solids

    PubMed Central

    Thomas, Simon F.; Rooks, Paul; Rudin, Fabian; Atkinson, Sov; Goddard, Paul; Bransgrove, Rachel M.; Mason, Paul T.; Allen, Michael J.

    2014-01-01

    We show in this study that the combination of a swirl flow reactor and an antimicrobial agent (in this case copper alginate beads) is a promising technique for the remediation of contaminated water in waste streams recalcitrant to UV-C treatment. This is demonstrated by comparing the viability of both common and UV-C resistant organisms in operating conditions where UV-C proves ineffective - notably high levels of solids and compounds which deflect UV-C. The swirl flow reactor is easy to construct from commonly available plumbing parts and may prove a versatile and powerful tool in waste water treatment in developing countries. PMID:25541706

  19. A comparison between ultraviolet disinfection and copper alginate beads within a vortex bioreactor for the deactivation of bacteria in simulated waste streams with high levels of colour, humic acid and suspended solids.

    PubMed

    Thomas, Simon F; Rooks, Paul; Rudin, Fabian; Atkinson, Sov; Goddard, Paul; Bransgrove, Rachel M; Mason, Paul T; Allen, Michael J

    2014-01-01

    We show in this study that the combination of a swirl flow reactor and an antimicrobial agent (in this case copper alginate beads) is a promising technique for the remediation of contaminated water in waste streams recalcitrant to UV-C treatment. This is demonstrated by comparing the viability of both common and UV-C resistant organisms in operating conditions where UV-C proves ineffective - notably high levels of solids and compounds which deflect UV-C. The swirl flow reactor is easy to construct from commonly available plumbing parts and may prove a versatile and powerful tool in waste water treatment in developing countries.

  20. Study of Alginate-Supported Ionic Liquid and Pd Catalysts

    PubMed Central

    Jouannin, Claire; Vincent, Chloë; Dez, Isabelle; Gaumont, Annie-Claude; Vincent, Thierry; Guibal, Eric

    2012-01-01

    New catalytic materials, based on palladium immobilized in ionic liquid supported on alginate, were elaborated. Alginate was associated with gelatin for the immobilization of ionic liquids (ILs) and the binding of palladium. These catalytic materials were designed in the form of highly porous monoliths (HPMs), in order to be used in a column reactor. The catalytic materials were tested for the hydrogenation of 4-nitroaniline (4-NA) in the presence of formic acid as hydrogen donor. The different parameters for the elaboration of the catalytic materials were studied and their impact analyzed in terms of microstructures, palladium sorption properties and catalytic performances. The characteristics of the biopolymer (proportion of β-D-mannuronic acid (M) and α-L-guluronic acid (G) in the biopolymer defined by the M/G ratio), the concentration of the porogen agent, and the type of coagulating agent significantly influenced catalytic performances. The freezing temperature had a significant impact on structural properties, but hardly affected the catalytic rate. Cellulose fibers were incorporated as mechanical strengthener into the catalytic materials, and allowed to enhance mechanical properties and catalytic efficiency but required increasing the amount of hydrogen donor for catalysis.

  1. Activation Mechanism and Cellular Localization of Membrane-Anchored Alginate Polymerase in Pseudomonas aeruginosa.

    PubMed

    Moradali, M Fata; Ghods, Shirin; Rehm, Bernd H A

    2017-03-03

    The exopolysaccharide, alginate, produced by the opportunistic human pathogen Pseudomonas aeruginosa represents a survival advantage by contributing to formation of characteristic biofilms during infection. Membrane anchored proteins Alg8 (catalytic subunit) and Alg44 (co-polymerase) constitute the alginate polymerase which is being activated by the second messenger molecule c-di-GMP, but the mechanism of activation remains elusive. To shed light on the c-di-GMP mediated activation of alginate polymerization in vivo, an in silico structural model of Alg8 fused to the c-di-GMP binding PilZ domain informed by the structure of cellulose synthase, BcsA, was developed. This structural model was probed by site-specific mutagenesis and different cellular levels of c-di-GMP. Results suggested that c-di-GMP-mediated activation of alginate polymerization involves amino acids residing at two loops including H323 (loop A), T457 and E460 (loop B) surrounding the catalytic site in the predicted model. Activity of respective Alg8 variants suggested that c-di-GMP-mediated control of substrate access to the catalytic site of Alg8 is dissimilar to the known activation mechanism of BcsA. Alg8 variants responded differently to various c-di-GMP levels while MucR imparted c-di-GMP for activation of alginate polymerase. Furthermore, we showed that Alg44 co-polymerase constituted a stable dimer, with its periplasmic domains required for protein localization, alginate polymerization and modification. Superfolder GFP fusions of Alg8 and Alg44 showed a non-uniform, punctuate and patchy arrangement of both proteins surrounding the cell. Overall, this study provides insights into the c-di-GMP mediated activation of alginate polymerization while assigning functional roles to Alg8 and Alg44 including their subcellular localization and distribution.IMPORTANCE The exopolysaccharide, alginate, is an important biofilm component of the opportunistic human pathogen P. aeruginosa and the principle

  2. Characterization of alginate-like exopolysaccharides isolated from aerobic granular sludge in pilot-plant.

    PubMed

    Lin, Yuemei; de Kreuk, Merle; van Loosdrecht, M C M; Adin, Avner

    2010-06-01

    To understand functional gel-forming exopolysaccharides in aerobic granular sludge, alginate-like exopolysaccharides were specifically extracted from aerobic granular sludge cultivated in a pilot plant treating municipal sewage. The exopolysaccharides were identified by the FAO/WHO alginate identification tests, characterized by biochemical assays, gelation with Ca(2+), blocks fractionation, spectroscopic analysis as UV-visible, FT-IR and MALDI-TOF MS, and electrophoresis. The yield of extractable alginate-like exopolysaccharides was reached 160+/-4mg/g (VSS ratio). They resembled seaweed alginate in UV-visible and MALDI-TOF MS spectra, and distinguished from it in the reactions with acid ferric sulfate, phenol-sulfuric acid and Coomassie brilliant blue G250. Characterized by their high percentage of poly guluronic acid blocks (69.07+/-8.95%), the isolated exopolysaccharides were capable to form rigid, non-deformable gels in CaCl(2). They were one of the dominant exopolysaccharides in aerobic granular sludge. We suggest that polymers play a significant role in providing aerobic granular sludge a highly hydrophobic, compact, strong and elastic structure.

  3. Adsorption and desorption of Zn(II) and Cu(II) on Ca- alginate immobilized activated rice bran

    NASA Astrophysics Data System (ADS)

    Suratman, A.; Kamalia, N. Z.; Kusumawati, W. A.

    2016-02-01

    Ca-alginate immobilized activated rice bran has been used for adsorption of Zn(II) and Cu(II) from aqueous solution. The effect of the pH, kinetics model, adsorption isotherm and desorption on the adsorption performance was investigated. Activated rice bran was immobilized by the entrapment in alginate beads. The adsorption strength of Ca-alginate immobilized activated rice bran was compared to Ca-alginate and non-immobilized activated rice bran. The concentrations of adsorbed ions were analyzed using Atomic Absorption Spectrophotometer (AAS). The result showed that pH of 4.0 and the contact time of 120 min are the optimum condition for adsorption of Zn(II) and Cu(II). The adsorption kinetic of Zn(II) and Cu(II) followed the pseudo-second-order model with adsorption rate constant 4.9 x 10-2 and 3.14 g.mg-1.min-1, respectively. The both adsorption processes obeyed Langmuir isotherm with adsorption capacity of 2.03 and 2.42 mg.g-1 of adsorbent, respectively. The strength of Zn adsorption on Ca-alginate immobilized activated rice bran (86.63%) was more effective compared to Ca-alginate beads (60.96%) and activated rice bran (43.85%). The strength of Cu adsorption was 80.00%, 61.50% and 22.10%, respectively. The desorption of Zn(II) and Cu(II) showed that recovery percentage of the adsorption was 76.56% and 57.80% with the condition of using HCl 0.1 M as desorption agent for 1 hour.

  4. Alginate/polyoxyethylene and alginate/gelatin hydrogels: preparation, characterization, and application in tissue engineering.

    PubMed

    Aroguz, Ayse Z; Baysal, Kemal; Adiguzel, Zelal; Baysal, Bahattin M

    2014-05-01

    Hydrogels are attractive biomaterials for three-dimensional cell culture and tissue engineering applications. The preparation of hydrogels using alginate and gelatin provides cross-linked hydrophilic polymers that can swell but do not dissolve in water. In this work, we first reinforced pure alginate by using polyoxyethylene as a supporting material. In an alginate/PEO sample that contains 20 % polyoxyethylene, we obtained a stable hydrogel for cell culture experiments. We also prepared a stable alginate/gelatin hydrogel by cross-linking a periodate-oxidized alginate with another functional component such as gelatin. The hydrogels were found to have a high fluid uptake. In this work, preparation, characterization, swelling, and surface properties of these scaffold materials were described. Lyophilized scaffolds obtained from hydrogels were used for cell viability experiments, and the results were presented in detail.

  5. Site-saturation engineering of lysine 47 in cyclodextrin glycosyltransferase from Paenibacillus macerans to enhance substrate specificity towards maltodextrin for enzymatic synthesis of 2-O-D-glucopyranosyl-L-ascorbic acid (AA-2G).

    PubMed

    Han, Ruizhi; Liu, Long; Shin, Hyun-dong; Chen, Rachel R; Du, Guocheng; Chen, Jian

    2013-07-01

    In this work, the site-saturation engineering of lysine 47 in cyclodextrin glycosyltransferase (CGTase) from Paenibacillus macerans was conducted to improve the specificity of CGTase towards maltodextrin, which can be used as a cheap and easily soluble glycosyl donor for the enzymatic synthesis of 2-O-D-glucopyranosyl-L-ascorbic acid (AA-2G) by CGTase. When using maltodextrin as glycosyl donor, four mutants K47F (lysine→ phenylalanine), K47L (lysine→ leucine), K47V (lysine→ valine) and K47W (lysine→ tryptophan) showed higher AA-2G yield as compared with that produced by the wild-type CGTase. The transformation conditions (temperature, pH and the mass ratio of L-ascorbic acid to maltodextrin) were optimized and the highest titer of AA-2G produced by the mutant K47L could reach 1.97 g/l, which was 64.2% higher than that (1.20 g/l) produced by the wild-type CGTase. The reaction kinetics analysis confirmed the enhanced maltodextrin specificity, and it was also found that compared with the wild-type CGTase, the four mutants had relatively lower cyclization activities and higher disproportionation activities, which was favorable for AA-2G synthesis. The mechanism responsible for the enhanced substrate specificity was further explored by structure modeling and it was indicated that the enhancement of maltodextrin specificity may be due to the short residue chain and the removal of hydrogen bonding interactions between the side chain of residue 47 and the sugar at -3 subsite. Here the obtained mutant CGTases, especially the K47L, has a great potential in the production of AA-2G with maltodextrin as a cheap and easily soluble substrate.

  6. Maximizing the utilization of Laminaria japonica as biomass via improvement of alginate lyase activity in a two-phase fermentation system.

    PubMed

    Oh, Yuri; Xu, Xu; Kim, Ji Young; Park, Jong Moon

    2015-08-01

    Brown seaweed contains up to 67% of carbohydrates by dry weight and presents high potential as a polysaccharide feedstock for biofuel production. To effectively use brown seaweed as a biomass, degradation of alginate is the major challenge due to its complicated structure and low solubility in water. This study focuses on the isolation of alginate degrading bacteria, determining of the optimum fermentation conditions, as well as comparing the conventional single fermentation system with the two-phase fermentation system which is separately using alginate and mannitol extracted from Laminaria japonica. Maximum yield of organic acids production and volatile solids reduction obtained were 0.516 g/g and 79.7%, respectively, using the two-phase fermentation system in which alginate fermentation was carried out at pH 7 and mannitol fermentation at pH 8. The two-phase fermentation system increased the yield of organic acids production by 1.14 times and led to a 1.45-times reduction of VS when compared to the conventional single fermentation system at pH 8. The results show that the two-phase fermentation system improved the utilization of alginate by separating alginate from mannitol leading to enhanced alginate lyase activity.

  7. Evaluation of the Effect of Psyllium on the Viability of Lactobacillus Acidophilus in Alginate-Polyl Lysine Beads

    PubMed Central

    Esmaeilzadeh, Jaleh; Nazemiyeh, Hossein; Maghsoodi, Maryam; Lotfipour, Farzaneh

    2016-01-01

    Purpose: Psylliumseeds are used in traditional herbal medicine to treat various disorders. Moreover, as a soluble fiber, psyllium has potential to stimulate bacterial growth in digestive system. We aimed to substitute alkali-extractable polysaccharides of psyllium for alginate in beads with second coat of poly-l-lysine to coat Lactobacillus acidophilus. Methods: Beads were prepared using extrusion technique. Poly-l-lysine as second coat was incorporated on optimum alginate/psyllium beads using immersion technique. Beads were characterized in terms of size, encapsulation efficiency, integrity and bacterial survival in harsh conditions. Results: Beads with narrow size distribution ranging from 1.85 ± 0.05 to 2.40 ± 0.18 mm with encapsulation efficiency higher than 96% were achieved. Psyllium concentrations in beads did not produce constant trend in bead sizes. Surface topography by SEM showed that substitution of psyllium enhanced integrity of obtained beads. Psyllium successfully protected the bacteria against acidic condition and lyophilization equal to alginate in the beads. Better survivability with beads of alginate/psyllium-poly-l-lysine was achieved with around 2 log rise in bacterial count in acid condition compared to the corresponding single coat beads. Conclusion: Alginate/psyllium (1:2) beads with narrow size distribution and high encapsulation efficiency of the bacteria have been achieved. Presence of psyllium produced a much smoother and integrated surface texture for the beads with sufficient protection of the bacteria against acidic condition as much as alginate. Considering the health benefits of psyllium and its prebiotic activity, psyllium can be beneficially replaced in part for alginate in probiotic coating. PMID:27766217

  8. Sargassum filipendula alginate from Brazil: seasonal influence and characteristics.

    PubMed

    Bertagnolli, Caroline; Espindola, Ana Paula D M; Kleinübing, Sirlei Jaiana; Tasic, Ljubica; da Silva, Meuris Gurgel Carlos

    2014-10-13

    The aim of this work is focused on the extraction and characterization of the Brazilian seaweed Sargassum filipendula alginate. Alginates obtained at different seasons were characterized by liquid state nuclear magnetic resonance spectroscopy and scanning electron microscopy. The alginate extraction efficiency was about 20%. Different seasons of the year and different stages in the life cycle of Sargassum sp. in southeastern Brazil influenced the M/G and, consequently, the technological properties of extracted alginates.

  9. Galactosylated alginate-curcumin micelles for enhanced delivery of curcumin to hepatocytes.

    PubMed

    Sarika, P R; James, Nirmala Rachel; Kumar, P R Anil; Raj, Deepa K

    2016-05-01

    Galactosylated alginate-curcumin conjugate (LANH2-Alg Ald-Cur) is synthesized for targeted delivery of curcumin to hepatocytes exploiting asialoglycoprotein receptor (ASGPR) on hepatocytes. The synthetic procedure includes oxidation of alginate (Alg), modification of lactobionic acid (LA), grafting of targeting group (modified lactobinic acid, LANH2) and conjugation of curcumin to alginate. Alginate-curcumin conjugate (Alg-Cur) without targeting group is also prepared for the comparison of properties. LANH2-Alg Ald-Cur self assembles to micelle with diameter of 235 ± 5 nm and zeta potential of -29 mV in water. Cytotoxicity analysis demonstrates enhanced toxicity of LANH2-Alg Ald-Cur over Alg-Cur on HepG2 cells. Cellular uptake studies confirm that LANH2-Alg Ald-Cur can selectively recognize HepG2 cells and shows higher internalization than Alg-Cur conjugate. Results indicate that LANH2-Alg Ald-Cur conjugate micelles are suitable candidates for targeted delivery of curcumin to HepG2 cells.

  10. Fabrication and characterization of macroporous epichlorohydrin cross-linked alginate beads as protein adsorbent.

    PubMed

    Zhang, Weican; Ji, Xiaofei; Sun, Caiyun; Lu, Xuemei

    2013-01-01

    Porous epichlorohydrin cross-linked alginate beads (ECAB) were prepared by the following method. Na-alginate solution containing Na2SO4 was introduced dropwise into CaCl2 solution to simultaneously form CaSO4 precipitate and Ca-alginate gel beads. The resultant beads were cross-linked with epichlorohydrin and then thoroughly washed with ethylenediamine tetraacetic acid (EDTA) solution to remove CaSO4. The structural features of porous ECAB were assessed with scanning electron microscopy (SEM) and experiments on water content and adsorption of bovine serum albumin (BSA). The results showed that macroporous ECAB can be obtained when the mass ratio of sodium sulfate to sodium alginate is 4:1. The adsorption behavior of the macroporous ECAB was well described by the Langmuir isotherm with maximum adsorption capacity equal to 740 mg BSA/g dry weight in 50 mM Na2HPO4-citric acid buffer (pH 4.0). BSA was more effectively adsorbed by macroporous ECAB at around pH 3 and the mechanism of the adsorption of BSA to the ECAB was ion exchange. Finally, experiments of a concentration of 1 mg/mL BSA using macroporous ECAB were performed.

  11. Preparation and characterization of alginate and psyllium beads containing Lactobacillus acidophilus.

    PubMed

    Lotfipour, Farzaneh; Mirzaeei, Shahla; Maghsoodi, Maryam

    2012-01-01

    This paper describes preparation and characterization of beads of alginate and psyllium containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Twelve different formulations containing alginate (ALG) and alginate-psyllium (ALG-PSL) were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology and surface properties, encapsulation efficiency, viabilities in acid (pH 1.8, 2 hours) and bile (0.5% w/v, 2 hours) conditions, and release in simulated colon pH conditions. The results showed that spherical beads with narrow size distribution ranging from 1.59 ± 0.04 to 1.67 ± 0.09 mm for ALG and from 1.61 ± 0.06 to 1.80 ± 0.07 mm for ALG-PSL with encapsulation efficiency higher than 98% were achieved. Furthermore, addition of PSL into ALG enhanced the integrity of prepared beads in comparison with ALG formulations. The results indicated that incorporation of PSL into alginate beads improved viability of the bacteria in acidic conditions as well as bile conditions. Also, stimulating effect of PSL on the probiotic bacteria was observed through 20-hour incubation in simulated colonic pH solution. According to our in vitro studies, PSL can be a suitable polymer candidate for partial substitution with ALG for probiotic coating.

  12. Alginate based hybrid copolymer hydrogels--influence of pore morphology on cell-material interaction.

    PubMed

    Gnanaprakasam Thankam, Finosh; Muthu, Jayabalan

    2014-11-04

    Alginate based hybrid copolymer hydrogels with unidirectional pore morphology were prepared to achieve synergistic biological performance for cardiac tissue engineering applications. Alginate based hybrid copolymer (ALGP) were prepared using alginate and poly(propylene fumarate) (HT-PPF) units. Different hybrid bimodal hydrogels were prepared by covalent crosslinking using poly(ethylene glycol diacrylate) and vinyl monomer viz acrylic acid, methyl methacrylate, butyl methacrylate and N-N'-methylene-bis-acrylamide and ionic crosslinking with calcium. The morphologically modified hydrogels (MM-hydrogels) with unidirectional elongated pores and high aspect ratio were prepared. MM-hydrogels favour better mechanical properties; it also enhances cell viability and infiltration due to unidirectional pores. However, the crosslinkers influence the fibroblast infiltration of these hydrogels. Synthesis of collagen and fibroblast infiltration was greater for alginate copolymer crosslinked with poly(ethylene glycol diacrylate-acrylic acid (ALGP-PA) even after one month (288%). This hybrid MM-hydrogel promoted cardiomyoblast growth on to their interstices signifying its potent applications in cardiac tissue engineering.

  13. Alginate copper oxide nano-biocomposite as a novel material for amperometric glucose biosensing.

    PubMed

    Buk, Vuslat; Emregul, Emel; Emregul, Kaan Cebesoy

    2017-05-01

    A novel amperometric glucose biosensor based on alginate-CuO nano-biocomposite and glucose oxidase (GOD) film was developed and characterized. The properties of the alginate-CuO-GOD film were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric measurements were employed to characterize the analytical performance of the biosensor. Several parameters including amount of alginate, concentration of GOD and cross-linkers, amount of CuO nanoparticles, and effect of pH were studied and optimized. Under optimal conditions, the developed alginate-CuO-GOD biosensor was shown to have two linear ranges; from 0.04mM to 3mM (with a correlation coefficient of 0.9996 and the sensitivity of 30.443μAmM(-1)cm(-2)) and from 4mM to 35mM (with a correlation coefficient of 0.9994 and the sensitivity of 7.205μAmM(-1)cm(-2)). The overall detection limit was estimated to be 1.6μM (signal-to-noise ratio of 3) and the Km value of 2.82mM. The biosensor exhibited rather good performance with long-term stability (remainder of activity is 78% after 15days) and significant specificity for glucose when compared to possible interfering molecules such as ascorbic acid, uric acid and acetaminophen.

  14. Preparation and Characterization of Alginate and Psyllium Beads Containing Lactobacillus acidophilus

    PubMed Central

    Lotfipour, Farzaneh; Mirzaeei, Shahla; Maghsoodi, Maryam

    2012-01-01

    This paper describes preparation and characterization of beads of alginate and psyllium containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Twelve different formulations containing alginate (ALG) and alginate-psyllium (ALG-PSL) were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology and surface properties, encapsulation efficiency, viabilities in acid (pH 1.8, 2 hours) and bile (0.5% w/v, 2 hours) conditions, and release in simulated colon pH conditions. The results showed that spherical beads with narrow size distribution ranging from 1.59 ± 0.04 to 1.67 ± 0.09 mm for ALG and from 1.61 ± 0.06 to 1.80 ± 0.07 mm for ALG-PSL with encapsulation efficiency higher than 98% were achieved. Furthermore, addition of PSL into ALG enhanced the integrity of prepared beads in comparison with ALG formulations. The results indicated that incorporation of PSL into alginate beads improved viability of the bacteria in acidic conditions as well as bile conditions. Also, stimulating effect of PSL on the probiotic bacteria was observed through 20-hour incubation in simulated colonic pH solution. According to our in vitro studies, PSL can be a suitable polymer candidate for partial substitution with ALG for probiotic coating. PMID:22649306

  15. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Propylene glycol alginate. 172.858 Section 172.858... Propylene glycol alginate. The food additive propylene glycol alginate (CAS Reg. No. 9005-37-2) may be used... the act: (1) The name of the additive, “propylene glycol alginate” or “propylene glycol ester...

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

    PubMed Central

    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

  17. Alginate lyases from alginate-degrading Vibrio splendidus 12B01 are endolytic.

    PubMed

    Badur, Ahmet H; Jagtap, Sujit Sadashiv; Yalamanchili, Geethika; Lee, Jung-Kul; Zhao, Huimin; Rao, Christopher V

    2015-03-01

    Alginate lyases are enzymes that degrade alginate through β-elimination of the glycosidic bond into smaller oligomers. We investigated the alginate lyases from Vibrio splendidus 12B01, a marine bacterioplankton species that can grow on alginate as its sole carbon source. We identified, purified, and characterized four polysaccharide lyase family 7 alginates lyases, AlyA, AlyB, AlyD, and AlyE, from V. splendidus 12B01. The four lyases were found to have optimal activity between pH 7.5 and 8.5 and at 20 to 25°C, consistent with their use in a marine environment. AlyA, AlyB, AlyD, and AlyE were found to exhibit a turnover number (kcat) for alginate of 0.60 ± 0.02 s(-1), 3.7 ± 0.3 s(-1), 4.5 ± 0.5 s(-1), and 7.1 ± 0.2 s(-1), respectively. The Km values of AlyA, AlyB, AlyD, and AlyE toward alginate were 36 ± 7 μM, 22 ± 5 μM, 60 ± 2 μM, and 123 ± 6 μM, respectively. AlyA and AlyB were found principally to cleave the β-1,4 bonds between β-d-mannuronate and α-l-guluronate and subunits; AlyD and AlyE were found to principally cleave the α-1,4 bonds involving α-l-guluronate subunits. The four alginate lyases degrade alginate into longer chains of oligomers.

  18. Alginate Lyases from Alginate-Degrading Vibrio splendidus 12B01 Are Endolytic

    PubMed Central

    Badur, Ahmet H.; Jagtap, Sujit Sadashiv; Yalamanchili, Geethika; Lee, Jung-Kul; Zhao, Huimin

    2015-01-01

    Alginate lyases are enzymes that degrade alginate through β-elimination of the glycosidic bond into smaller oligomers. We investigated the alginate lyases from Vibrio splendidus 12B01, a marine bacterioplankton species that can grow on alginate as its sole carbon source. We identified, purified, and characterized four polysaccharide lyase family 7 alginates lyases, AlyA, AlyB, AlyD, and AlyE, from V. splendidus 12B01. The four lyases were found to have optimal activity between pH 7.5 and 8.5 and at 20 to 25°C, consistent with their use in a marine environment. AlyA, AlyB, AlyD, and AlyE were found to exhibit a turnover number (kcat) for alginate of 0.60 ± 0.02 s−1, 3.7 ± 0.3 s−1, 4.5 ± 0.5 s−1, and 7.1 ± 0.2 s−1, respectively. The Km values of AlyA, AlyB, AlyD, and AlyE toward alginate were 36 ± 7 μM, 22 ± 5 μM, 60 ± 2 μM, and 123 ± 6 μM, respectively. AlyA and AlyB were found principally to cleave the β-1,4 bonds between β-d-mannuronate and α-l-guluronate and subunits; AlyD and AlyE were found to principally cleave the α-1,4 bonds involving α-l-guluronate subunits. The four alginate lyases degrade alginate into longer chains of oligomers. PMID:25556193

  19. Role of Calcium Alginate and Mannitol in Protecting Bifidobacterium

    PubMed Central

    Dianawati, Dianawati; Mishra, Vijay

    2012-01-01

    Fourier transform infrared (FTIR) spectroscopy was carried out to ascertain the mechanism of Ca-alginate and mannitol protection of cell envelope components and secondary proteins of Bifidobacterium animalis subsp. lactis Bb12 after freeze-drying and after 10 weeks of storage at room temperature (25°C) at low water activities (aw) of 0.07, 0.1, and 0.2. Preparation of Ca-alginate and Ca-alginate-mannitol as microencapsulants was carried out by dropping an alginate or alginate-mannitol emulsion containing bacteria using a burette into CaCl2 solution to obtain Ca-alginate beads and Ca-alginate-mannitol beads, respectively. The wet beads were then freeze-dried. The aw of freeze-dried beads was then adjusted to 0.07, 0.1, and 0.2 using saturated salt solutions; controls were prepared by keeping Ca-alginate and Ca-alginate-mannitol in aluminum foil without aw adjustment. Mannitol in the Ca-alginate system interacted with cell envelopes during freeze-drying and during storage at low aws. In contrast, Ca-alginate protected cell envelopes after freeze-drying but not during 10-week storage. Unlike Ca-alginate, Ca-alginate-mannitol was effective in retarding the changes in secondary proteins during freeze-drying and during 10 weeks of storage at low aws. It appears that Ca-alginate-mannitol is more effective than Ca-alginate in preserving cell envelopes and proteins after freeze-drying and after 10 weeks of storage at room temperature (25°C). PMID:22843535

  20. Impact of preharvest and postharvest alginate treatments enriched with vanillin on postharvest decay, biochemical properties, quality and sensory attributes of table grapes.

    PubMed

    Konuk Takma, Dilara; Korel, Figen

    2017-04-15

    Alginate solution enriched with vanillin as a bioactive compound was investigated for improving preharvest and postharvest quality and safety of table grapes. Alginate treatments with or without vanillin as preharvest spray and postharvest coating were implemented on table grapes of Alphonse Lavalleé and Razaki cultivars. Fungal decay, biochemical properties, quality and sensory attributes were evaluated at day of preharvest treatment, at harvesting and during 35days of storage at 4±2°C. Alginate treatments with or without vanillin were effective in preventing weight and firmness losses. Total soluble solids, titratable acidity, and color of grapes coated with alginate coatings with or without vanillin showed minor changes compared to control grapes. Alginate coating incorporating vanillin provided significant reduction (1.73log CFU/g) in yeast-mold growth. Moreover, the coatings maintained greater total phenolic content and antioxidant activity compared to others during postharvest storage. In terms of sensory attributes, appearance was ranked as the highest for alginate coating without vanillin due to glossiness of alginate.

  1. Mobility of atrazine from alginate-bentonite controlled release formulations in layered soil.

    PubMed

    Fernández-Pérez, M; González-Pradas, E; Villafranca-Sánchez, M; Flores-Céspedes, F

    2001-04-01

    The mobility of atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine] from alginate-bentonite-based controlled release (CR) formulations was investigated by using soil columns. Two CR formulations based on sodium alginate (14.0 g kg(-1), atrazine (6.0 g kg(-1), natural or acid-treated bentonite (50 g kg(-1), and water (924 g kg(-1) were compared to technical grade product and commercial liquid (CL) formulation (Gesaprim 500FW). All herbicide treatments were applied to duplicate layered bed systems simulating the typical arrangement under a plastic greenhouse, which is composed of sand (10 cm), peat (2 cm), amended soil (20 cm) and native soil (20 cm). The columns were leached with 39 cm (1500 ml) and 156 cm (6000 ml) of 0.02 M CaCl2 solution to evaluate the effect of water volume applied on herbicide movement. When 39 cm of 0.02 M CaCl2 solution was applied, there was no presence of herbicide in the leachate for the alginate-bentonite CR treatments. However, 0.11% and 0.14% of atrazine appeared in the leachate when the treatment was carried out with technical grade and CL formulations, respectively. When 156 cm of 0.02 M CaCl2 solution was applied, the use of the alginate-acid treated bentonite CR formulation retards and reduces the presence of atrazine in the leachate as compared to technical product. Analysis of the soil columns showed the highest atrazine concentration in the peat layer. Alginate-bentonite CR formulations might be an efficient system for reducing atrazine leaching in layered soil and thus, it could reduce the risks of pollution of groundwater.

  2. Non-redox modulated fluorescence strategy for sensitive and selective ascorbic acid detection with highly photoluminescent nitrogen-doped carbon nanoparticles via solid-state synthesis.

    PubMed

    Zhu, Xiaohua; Zhao, Tingbi; Nie, Zhou; Liu, Yang; Yao, Shouzhuo

    2015-08-18

    Highly photoluminescent nitrogen-doped carbon nanoparticles (N-CNPs) were prepared by a simple and green route employing sodium alginate as a carbon source and tryptophan as both a nitrogen source and a functional monomer. The as-synthesized N-CNPs exhibited excellent water solubility and biocompatibility with a fluorescence quantum yield of 47.9%. The fluorescence of the N-CNPs was intensively suppressed by the addition of ascorbic acid (AA). The mechanism of the fluorescence suppression of the N-CNPs was investigated, and the synergistic action of the inner filter effect (IFE) and the static quenching effect (SQE) contributed to the intensive fluorescence suppression, which was different from those reported for the traditional redox-based fluorescent probes. Owing to the spatial effect and hydrogen bond between the AA and the groups on the N-CNP surface, excellent sensitivity and selectivity for AA detecting was obtained in a wide linear relationship from 0.2 μM to 150 μM. The detection limit was as low as 50 nM (signal-to-noise ratio of 3). The proposed sensing systems also represented excellent sensitivity and selectivity for AA analysis in human biological fluids, providing a valuable platform for AA sensing in clinic diagnostic and drug screening.

  3. Alginate-based bipolymeric-nanobioceramic composite matrices for sustained drug release.

    PubMed

    Hasnain, M Saquib; Nayak, Amit Kumar; Singh, Mukul; Tabish, Mohammad; Ansari, Mohammed Tahir; Ara, Tahseen Jahan

    2016-02-01

    Alginate-based bipolymeric-nanobioceramic composite matrices for sustained drug release were developed through incorporation of nano-hydroxyapatite [nHAp] powders within ionotropically-gelled calcium ion-induced alginate-poly (vinyl pyrrolidone) blends polymeric systems. nHAp powders were synthesized by precipitation technique using calcium hydroxide [Ca(OH)2] and orthophosphoric acid [H3PO4] as raw materials. The average particle size of these was synthesized. nHAp powders was found as 19.04 nm and used to prepare nHAp-alginate-PVP beads containing DS. These beads exhibited drug entrapment efficiency (%) of 65.82±1.88 to 94.45±3.72% and average bead sizes of 0.98±0.07 to 1.23±0.15 mm. These beads were characterized by scanning electron microscopy (SEM) and Fourier transform-infra red (FTIR) spectroscopy analyses. Various nHAp-alginate-PVP beads containing DS exhibited prolonged sustained drug release and followed the Koresmeyer-Peppas model of drug release (R2=0.9908-0.9978) with non-Fickian release (anomalous transport) mechanism (n=0.73-0.84) for drug release over 8 h.

  4. Alginate hydrogel-mediated crystallization of calcium carbonate

    SciTech Connect

    Ma, Yufei; Feng, Qingling

    2011-05-15

    We documented a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system for the purpose of understanding the mediating function of alginate on the crystallization of calcium carbonate. The alginate was involved in the nucleation and the growth process of CaCO{sub 3}. The crystal size, morphology and roughness of crystal surface were significantly influenced by the type of the alginate, which could be accounted for by the length of the G blocks in alginate. A combination of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that there were the chemical interactions between the alginate and the mineral phase. This strategic approach revealed the biologically controlled CaCO{sub 3} mineralization within calcium alginate hydrogels via the selective nucleation and the confined crystallization of CaCO{sub 3}. The results presented here could contribute to the understanding of the mineralization process in hydrogel systems. -- Graphical abstract: Schematic illustration of the growth of calcite aggregates with different morphologies obtained from (a) Low G alginate gels and (b) High G alginate gels. Display Omitted highlights: > We use a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system to understand the mediating function of alginate on the crystallization of CaCO{sub 3} crystals. > The crystal size, morphology and crystal surface roughness are influenced by the length of G blocks in alginate. There are chemical interactions between the alginate and the mineral phase. > We propose a potential mechanism of CaCO{sub 3} crystallization within High G and Low G calcium alginate hydrogel.

  5. Highly stable and magnetically separable alginate/Fe3O4 composite for the removal of strontium (Sr) from seawater.

    PubMed

    Hong, Hye-Jin; Jeong, Hyeon Su; Kim, Byoung-Gyu; Hong, Jeongsik; Park, In-Su; Ryu, Taegong; Chung, Kang-Sup; Kim, Hyuncheol; Ryu, Jungho

    2016-12-01

    In this study, a highly stable alginate/Fe3O4 composite was synthesized, and systematically investigated for the practical application of strontium (Sr) removal in complex media, such as seawater and radioactive wastewater. To overcome the drawbacks of the use of alginate microspheres, high contents of alginic acid and Fe3O4 were used to provide a more rigid structure with little swelling and facile separation, respectively. The synthesized composite was optimized for particle sizes of <400 μm and 1% content of Fe3O4. The alginate/Fe3O4 composite showed excellent Sr uptake (≈400.0 mg/g) and exhibited outstanding selectivity for Sr among various cations (Na, Mg, Ca and K). However, in diluted Sr condition (50 mg/L), Ca significantly affected Sr adsorption, resulting in a decrease of Kd value from 3.7 to 2.4 at the 0.01 M Ca. The alginate/Fe3O4 composite could be completely regenerated using 0.1 M HCl and CaCl2. In real seawater spiked with 50 mg/L of Sr, the alginate/Fe3O4 composite showed 12.5 mg/g of Sr uptake, despite the highly concentrated ions in seawater. The adsorption experiment for radio-active (90)Sr revealed a removal efficiency of 67% in real seawater, demonstrating the reliability of the alginate/Fe3O4 composite.

  6. Effect of nutrients on alginate synthesis in Azotobacter vinelandii and characterization of the produced alginate.

    PubMed

    Sabry, S A; Ghanem, K M; Sabra, W A

    1996-12-01

    The role of nutrients on alginate production by Azotobacter vinelandii was studied in batch cultures. The largest amount of bacterial alginate was obtained in presence of: 0.3 g/l MgSO4.7H2O. 0.4 g/l NaCl, 42 mg/l CaCl2.2H2O,.4 mg/l KH2PO4, 16 mg/l K2HPO4, 2.5 mg/l FeSO4.7H2O, 2.9 mg/l H3BO3, 2 mg/l ZnSO4.7H2O, 2 mg/l Na2MoO4.2H2O, 0.3 mg/l CuSO4.5H2O, 0.2 mg/l MnCl2.4H2O. Alginate production was not enhanced by natural additives or inducing agents, except for acetate, which increased alginate yield. The pure alginate contained 0.36% ash and 0.4% protein. It is similar to algal alginate, but it has an extra acetyl group. It contains 69.5% M-M block, 27.5% M-G block and 3% G-G block.

  7. Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.

    PubMed

    Cataldo, Salvatore; Gianguzza, Antonio; Milea, Demetrio; Muratore, Nicola; Pettignano, Alberto

    2016-11-01

    The adsorption capacity of an activated carbon - calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH=5, in NaCl medium and in the ionic strength range 0.1-0.75molL(-1). Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate (AA-Ca) improves the adsorption capacity (qm) of active carbon (AC) in the ACAA-Ca adsorbent material (e.g., qm=15.7 and 10.5mgg(-1) at I=0.25molL(-1), for ACAA-Ca and AC, respectively). SEM-EDX and thermogravimetric (TGA) measurements were carried out in order to characterize the composite material. The results of the speciation study on the Pb(II) solution and of the characterization of the ACAA-Ca and of the pristine AA-Ca and AC were evaluated in order to explain the specific contribution of AC and AA-Ca to the adsorption of the metal ion.

  8. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... use in food (as served) (percent) Functional use Baked goods, § 170.3(n)(1) of this chapter 0.002... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium alginate. 184.1187 Section 184.1187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  9. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...: Category of food Maximum level of use in food (as served) (percent) Functional use Confections, frostings... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ammonium alginate. 184.1133 Section 184.1133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  10. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2010 CFR

    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...

  11. An analytic study on the effect of alginate on the velocity profiles of blood in rectangular microchannels using microparticle image velocimetry.

    PubMed

    Pitts, Katie L; Fenech, Marianne

    2013-01-01

    It is desired to understand the effect of alginic acid sodium salt from brown algae (alginate) as a viscosity modifier on the behavior of blood in vitro using a micro-particle image velocimetry (µPIV) system. The effect of alginate on the shape of the velocity profile, the flow rate and the maximum velocity achieved in rectangular microchannels channels are measured. The channels were constructed of polydimethylsiloxane (PDMS), a biocompatible silicone. Porcine blood cells suspended in saline was used as the working fluid at twenty percent hematocrit (H = 20). While alginate was only found to have minimal effect on the maximum velocity and the flow rate achieved, it was found to significantly affect the shear rate at the wall by between eight to a hundred percent.

  12. Innate immune-stimulating and immune genes up-regulating activities of three types of alginate from Sargassum siliquosum in Pacific white shrimp, Litopenaeus vannamei.

    PubMed

    Yudiati, Ervia; Isnansetyo, Alim; Murwantoko; Ayuningtyas; Triyanto; Handayani, Christina Retna

    2016-07-01

    The Total Haemocyte Count (THC), phenoloxidase (PO), Superoxide Dismutase (SOD) activity, Phagocytic Activity/Index and Total Protein Plasma (TPP) were examined after feeding the white shrimp Litopenaeus vannamei with diets supplemented with three different types of alginates (acid, calcium and sodium alginates). Immune-related genes expression was evaluated by quantitative Real Time PCR (qRT-PCR). Results indicated that the immune parameters directly increased according to the doses of alginates and time. The 2.0 g kg(-1) of acid and sodium alginate treatments were gave better results. Four immune-related genes expression i.e. LGBP, Toll, Lectin, proPO were up regulated. It is therefore concluded that the supplementation of alginate of Sargassum siliquosum on the diet of L. vannamei enhanced the innate immunity as well as the expression of immune-related genes. It is the first report on the simultaneous evaluation of three alginate types to enhance innate immune parameters and immune-related genes expression in L. vannamei.

  13. Alginate composites for bone tissue engineering: a review.

    PubMed

    Venkatesan, Jayachandran; Bhatnagar, Ira; Manivasagan, Panchanathan; Kang, Kyong-Hwa; Kim, Se-Kwon

    2015-01-01

    Bone is a complex and hierarchical tissue consisting of nano hydroxyapatite and collagen as major portion. Several attempts have been made to prepare the artificial bone so as to replace the autograft and allograft treatment. Tissue engineering is a promising approach to solve the several issues and is also useful in the construction of artificial bone with materials including polymer, ceramics, metals, cells and growth factors. Composites consisting of polymer-ceramics, best mimic the natural functions of bone. Alginate, an anionic polymer owing enormous biomedical applications, is gaining importance particularly in bone tissue engineering due to its biocompatibility and gel forming properties. Several composites such as alginate-polymer (PLGA, PEG and chitosan), alginate-protein (collagen and gelatin), alginate-ceramic, alginate-bioglass, alginate-biosilica, alginate-bone morphogenetic protein-2 and RGD peptides composite have been investigated till date. These alginate composites show enhanced biochemical significance in terms of porosity, mechanical strength, cell adhesion, biocompatibility, cell proliferation, alkaline phosphatase increase, excellent mineralization and osteogenic differentiation. Hence, alginate based composite biomaterials will be promising for bone tissue regeneration. This review will provide a broad overview of alginate preparation and its applications towards bone tissue engineering.

  14. Adsorption of CO2 by alginate immobilized zeolite beads

    NASA Astrophysics Data System (ADS)

    Suratman, A.; Kunarti, E. S.; Aprilita, N. H.; Pamurtya, I. C.

    2017-03-01

    Immobilized zeolit in alginate beads for adsorption of CO2 was developed. Alginate immobilized zeolit beads was generated by dropping the mixture of Na-alginate and zeolite solution into Ca2+ solution. The adsorption efficacy such as the influence of contact time, mass of zeolite, flowrate of CO2, and mass of adsorbent was evaluated. The adsorption of CO2 onto alginate immobilized zeolit beads was investigated by performing both equilibrium and kinetic batch test. Bead was characterized by FTIR and SEM. Alginate immobilized zeolit beads demonstrated significantly higher sorption efficacy compared to plain alginate beads and zeolite with 0.25 mmol CO2 adsorbed /g adsorbent. Optimum condition was achieved with mass composition of alginate:zeolite (3:1), flowrate 50 mL/min for 20 minutes. The alginate immobilized zeolit beads showed that adsorption of CO2 followed Freundlich isotherm and pseudo second order kinetic model. Adsorption of CO2 onto alginate immobilized zeolite beads is a physisorption with adsorption energy of 6.37 kJ/mol. This results indicates that the alginate immobilized zeolit beads can be used as promising adsorbents for CO2.

  15. Activity of vegetative insecticidal proteins Vip3Aa58 and Vip3Aa59 of Bacillus thuringiensis against lepidopteran pests.

    PubMed

    Baranek, Jakub; Kaznowski, Adam; Konecka, Edyta; Naimov, Samir

    2015-09-01

    Vegetative insecticidal proteins (Vips) secreted by some isolates of Bacillus thuringiensis show activity against insects and are regarded as insecticides against pests. A number of B. thuringiensis strains harbouring vip3A genes were isolated from different sources and identified by using a PCR based approach. The isolates with the highest insecticidal activity were indicated in screening tests, and their vip genes were cloned and sequenced. The analysis revealed two polymorphic Vip protein forms, which were classified as Vip3Aa58 and Vip3Aa59. After expression of the vip genes, the proteins were isolated and characterized. The activity of both toxins was estimated against economically important lepidopteran pests of woodlands (Dendrolimus pini), orchards (Cydia pomonella) and field crops (Spodoptera exigua). Vip3Aa58 and Vip3Aa59 were highly toxic and their potency surpassed those of many Cry proteins used in commercial bioinsecticides. Vip3Aa59 revealed similar larvicidal activity as Vip3Aa58 against S. exigua and C. pomonella. Despite 98% similarity of amino acid sequences of both proteins, Vip3Aa59 was significantly more active against D. pini. Additionally the effect of proteolytic activation of Vip58Aa and Vip3Aa59 on toxicity of D. pini and S. exigua was studied. Both Vip3Aa proteins did not show any activity against Tenebrio molitor (Coleoptera) larvae. The results suggest that the Vip3Aa58 and Vip3Aa59 toxins might be useful for controlling populations of insect pests of crops and forests.

  16. Mechanical spectroscopy and relaxometry on alginate hydrogels: a comparative analysis for structural characterization and network mesh size determination.

    PubMed

    Turco, Gianluca; Donati, Ivan; Grassi, Mario; Marchioli, Giulia; Lapasin, Romano; Paoletti, Sergio

    2011-04-11

    The structure of calcium-saturated alginate hydrogels has been studied by combining rheological determinations and relaxometry measurements. The mechanical spectroscopy analyses performed on alginate gel cylinders at different polysaccharide concentration allowed estimating their main structural features such as the average mesh size. The calculation was based on the introduction of a front factor in the classical rubber elasticity approach which was correlated to the average length of the Guluronic acid blocks along the polysaccharide chain. Transverse relaxation time (T(2)) determinations performed on the cylinders revealed the presence of two relaxation rates of the water entrapped within the hydrogel network. The cross-correlation of the latter data with the rheological measurements allowed estimating the mesh size distribution of the hydrogel network. The results obtained for the hydrogel cylinders were found to be consistent with the relaxometric analysis performed on the alginate microbeads where, however, only one type of water bound into the network structure was detected. A good correlation was found in the average mesh size determined by means of relaxometric measurements on alginate microbeads and by a statistical analysis performed on TEM micrographs. Finally, the addition of a solution containing calcium ions allowed investigating further the different water relaxation modes within alginate hydrogels.

  17. Copper(II)-mediated thermolysis of alginates: a model kinetic study on the influence of metal ions in the thermochemical processing of macroalgae

    PubMed Central

    Rowbotham, J. S.; Dyer, P. W.; Greenwell, H. C.; Selby, D.; Theodorou, M. K.

    2013-01-01

    Thermochemical processing methods such as pyrolysis are of growing interest as a means of converting biomass into fuels and commodity chemicals in a sustainable manner. Macroalgae, or seaweed, represent a novel class of feedstock for pyrolysis that, owing to the nature of the environments in which they grow coupled with their biochemistry, naturally possess high metal contents. Although the impact of metals upon the pyrolysis of terrestrial biomass is well documented, their influence on the thermochemical conversion of marine-derived feeds is largely unknown. Furthermore, these effects are inherently difficult to study, owing to the heterogeneous character of natural seaweed samples. The work described in this paper uses copper(II) alginate, together with alginic acid and sodium alginate as model compounds for exploring the effects of metals upon macroalgae thermolysis. A thermogravimetric analysis–Fourier transform infrared spectroscopic study revealed that, unusually, Cu2+ ions promote the onset of pyrolysis in the alginate polymer, with copper(II) alginate initiating rapid devolatilization at 143°C, 14°C lower than alginic acid and 61°C below the equivalent point for sodium alginate. Moreover, this effect was mirrored in a sample of wild Laminaria digitata that had been doped with Cu2+ ions prior to pyrolysis, thus validating the use of alginates as model compounds with which to study the thermolysis of macroalgae. These observations indicate the varying impact of different metal species on thermochemical behaviour of seaweeds and offer an insight into the pyrolysis of brown macroalgae used in phytoremediation of metal-containing waste streams. PMID:24427515

  18. Physical characterization of alginate-Pluronic F127 gel for endoluminal NABDs delivery.

    PubMed

    Abrami, Michela; D'Agostino, Ilenia; Milcovich, Gesmi; Fiorentino, Simona; Farra, Rossella; Asaro, Fioretta; Lapasin, Romano; Grassi, Gabriele; Grassi, Mario

    2014-02-07

    Here we focus the attention on the physical characteristics of a highly biocompatible hydrogel made up of crosslinked alginate and Pluronic F127 (PF127). This is a composite polymeric blend we propose for artery endoluminal delivery of an emerging class of molecules named nucleic acid based drugs (NABDs). The physical characterization of our composite gel, i.e. mesh size distribution and PF127-alginate mutual organization after crosslinking, can significantly determine the NABDs release kinetics. Thus, to explore these aspects, different technical approaches, i.e. rheology, low/high field NMR and TEM, were used. While rheology provided information at the macroscopic and nano-level, the other three approaches gave details at the nano-level. We observe that Pluronic micelles, organizing in cubic ordered domains, generate, upon alginate crosslinking, the formation of meshes (≈ 150 nm) larger than those occurring in a Pluronic-free alginate network (≈ 25 nm). Nevertheless, smaller alginate meshes are still on and can just host un-structured Pluronic micelles and water. Accordingly, the gel structure is quite inhomogeneous, where big meshes (filled by crystalline Pluronic) co-exist with smaller meshes (hosting water and un-structured PF127 micelles). While big meshes offer a considerable hindering action on a diffusing solute, smaller ones represent a sort of free space where solute diffusion is faster. The presence of big and small meshes indicates that drug release may follow a double kinetics characterized by a fast and slow release. Notably, this behavior is considered appropriate for endoluminal drug release to the arterial wall.

  19. Inter-grade and inter-batch variability of sodium alginate used in alginate-based matrix tablets.

    PubMed

    Fu, Shao; Buckner, Ira S; Block, Lawrence H

    2014-10-01

    The purpose of this study is to characterize the inter-grade and inter-batch variability of sodium alginate used in the formulation of matrix tablets. Four different grades and three batches of one grade of sodium alginate were used to prepare matrix tablets. Swelling, erosion, and drug release tests of sodium alginate matrix tablets were conducted in a USP dissolution apparatus. Substantial differences in swelling and erosion behavior of sodium alginate matrix tablets were evident among different viscosity grades. Even different batches of the same grade exhibit substantial differences in the swelling and erosion behavior of their matrix tablets. The erosion behavior of sodium alginate matrix tablets can be partly explained by their rheological properties (both apparent viscosity and viscoelasticity) in solution. Sodium alginate with higher apparent viscosity and viscoelasticity in solution show slower erosion rate and higher swelling rate. Compacts prepared from grades or batches with higher viscosity and higher viscoelasticity show slower drug release. For grades or batches with similar apparent viscosities, apparent viscosities of sodium alginate solution at low concentration alone are not sufficient to predict the functionality of sodium alginate in matrix tablets. Viscoelastic properties of sodium alginate solutions at one high concentration corresponding to the polymer gel state, may be suitable indicia of the extended release behavior of sodium alginate matrix tablets.

  20. Production of polyhydroxybutyrate and alginate from glycerol by Azotobacter vinelandii under nitrogen-free conditions.

    PubMed

    Yoneyama, Fuminori; Yamamoto, Mayumi; Hashimoto, Wataru; Murata, Kousaku

    2015-01-01

    Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-d-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including γ-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source.

  1. Production of polyhydroxybutyrate and alginate from glycerol by Azotobacter vinelandii under nitrogen-free conditions

    PubMed Central

    Yoneyama, Fuminori; Yamamoto, Mayumi; Hashimoto, Wataru; Murata, Kousaku

    2015-01-01

    Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-d-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including γ-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source. PMID:25880041

  2. Alginate therapy is effective treatment for gastroesophageal reflux disease symptoms: a systematic review and meta-analysis.

    PubMed

    Leiman, D A; Riff, B P; Morgan, S; Metz, D C; Falk, G W; French, B; Umscheid, C A; Lewis, J D

    2016-09-26

    In patients with gastroesophageal reflux disease (GERD) and erosive esophagitis, treatment with proton pump inhibitors (PPIs) is highly effective. However, in some patients, especially those with non-erosive reflux disease or atypical GERD symptoms, acid suppressive therapy with PPIs is not as successful. Alginates are medications that work through an alternative mechanism by displacing the post-prandial gastric acid pocket. We performed a systematic review and meta-analysis to examine the benefit of alginate-containing compounds in the treatment of patients with symptoms of GERD.PubMed/MEDLINE, Embase and the Cochrane library electronic databases were searched through October 2015 for randomized controlled trials comparing alginate-containing compounds to placebo, antacids, histamine-2 receptor antagonists (H2RAs) or PPIs for the treatment of GERD symptoms. Additional studies were identified through bibliography review. Non-English studies and those with pediatric patients were excluded. Meta-analyses were performed using random-effects models to calculate odds ratios (OR). Heterogeneity between studies was estimated using the I(2) statistic. Analyses were stratified by type of comparator. The search strategy yielded 665 studies and 15 (2.3%) met inclusion criteria. Fourteen were included in the meta-analysis (N = 2095 subjects). Alginate-based therapies increased the odds of resolution of GERD symptoms when compared to placebo or antacids (OR: 4.42; 95% CI 2.45-7.97) with a moderate degree of heterogeneity between studies (I(2)  = 71%, P = .001). Compared to PPIs or H2RAs, alginates appear less effective but the pooled estimate was not statistically significant (OR: 0.58; 95% CI 0.27-1.22). Alginates are more effective than placebo or antacids for treating GERD symptoms.

  3. Design and construction of a synthetic Bacillus thuringiensis Cry4Aa gene: hyperexpression in Escherichia coli.

    PubMed

    Hayakawa, Tohru; Howlader, Mohammad Tofazzal Hossain; Yamagiwa, Masashi; Sakai, Hiroshi

    2008-10-01

    Cry4Aa produced by Bacillus thuringiensis is a dipteran-specific toxin and is, therefore, of great interest for developing a bioinsecticide to control mosquitoes. However, the expression of Cry4Aa in Escherichia coli is relatively low, which is a major disadvantage in its development as a bioinsecticide. In this study, to establish an effective production system, a 1,914-bp modified gene (cry4Aa-S1) encoding Cry4Aa was designed and synthesized in accordance with the G + C content and codon preference of E. coli genes without altering the encoded amino acid sequence. The cry4Aa-S1 gene allowed a significant improvement in expression level, over five-fold, compared to that of the original cry4Aa gene. The product of the cry4Aa-S1 gene showed the same level of insecticidal activity against Culex pipiens larvae as that from cry4Aa. This suggested that unfavorable codon usage was one of the reasons for poor expression of cry4Aa in E. coli, and, therefore, changing the cry4Aa codons to accord with the codon usage in E. coli led to efficient production of Cry4Aa. Efficient production of Cry4Aa in E. coli can be a powerful measure to prepare a sufficient amount of Cry4Aa protein for both basic analytical and applied researches.

  4. Single amino acid insertions in extracellular loop 2 of Bombyx mori ABCC2 disrupt its receptor function for Bacillus thuringiensis Cry1Ab and Cry1Ac but not Cry1Aa toxins.

    PubMed

    Tanaka, Shiho; Miyamoto, Kazuhisa; Noda, Hiroaki; Endo, Haruka; Kikuta, Shingo; Sato, Ryoichi

    2016-04-01

    In a previous report, seven Cry1Ab-resistant strains were identified in the silkworm, Bombyx mori; these strains were shown to have a tyrosine insertion at position 234 in extracellular loop 2 of the ABC transporter C2 (BmABCC2). This insertion was confirmed to destroy the receptor function of BmABCC2 and confer the strains resistance against Cry1Ab and Cry1Ac. However, these strains were susceptible to Cry1Aa. In this report, we examined the mechanisms of the loss of receptor function of the transporter by expressing mutations in Sf9 cells. After replacement of one or two of the five amino acid residues in loop 2 of the susceptible BmABCC2 gene [BmABCC2_S] with alanine, cells still showed susceptibility, retaining the receptor function. Five mutants with single amino acid insertions at position 234 in BmABCC2 were also generated, resulting in loop 2 having six amino acids, which corresponds to replacing the tyrosine insertion in the resistant BmABCC2 gene [BmABCC2_R(+(234)Y)] with another amino acid. All five mutants exhibited loss of function against Cry1Ab and Cry1Ac. These results suggest that the amino acid sequence in loop 2 is less important than the loop size (five vs. six amino acids) or loop structure for Cry1Ab and Cry1Ac activity. Several domain-swapped mutant toxins were then generated among Cry1Aa, Cry1Ab, and Cry1Ac, which are composed of three domains. Swapped mutants containing domain II of Cry1Ab or Cry1Ac did not kill Sf9 cells expressing BmABCC2_R(+(234)Y), suggesting that domain II of the Cry toxin is related to the interaction with the receptor function of BmABCC2. This also suggests that different reactions against Bt-toxins in some B. mori strains, that is, Cry1Ab resistance or Cry1Aa susceptibility, are attributable to structural differences in domain II of Cry1A toxins.

  5. Versatile click alginate hydrogels crosslinked via tetrazine-norbornene chemistry.

    PubMed

    Desai, Rajiv M; Koshy, Sandeep T; Hilderbrand, Scott A; Mooney, David J; Joshi, Neel S

    2015-05-01

    Alginate hydrogels are well-characterized, biologically inert materials that are used in many biomedical applications for the delivery of drugs, proteins, and cells. Unfortunately, canonical covalently crosslinked alginate hydrogels are formed using chemical strategies that can be biologically harmful due to their lack of chemoselectivity. In this work we introduce tetrazine and norbornene groups to alginate polymer chains and subsequently form covalently crosslinked click alginate hydrogels capable of encapsulating cells without damaging them. The rapid, bioorthogonal, and specific click reaction is irreversible and allows for easy incorporation of cells with high post-encapsulation viability. The swelling and mechanical properties of the click alginate hydrogel can be tuned via the total polymer concentration and the stoichiometric ratio of the complementary click functional groups. The click alginate hydrogel can be modified after gelation to display cell adhesion peptides for 2D cell culture using thiol-ene chemistry. Furthermore, click alginate hydrogels are minimally inflammatory, maintain structural integrity over several months, and reject cell infiltration when injected subcutaneously in mice. Click alginate hydrogels combine the numerous benefits of alginate hydrogels with powerful bioorthogonal click chemistry for use in tissue engineering applications involving the stable encapsulation or delivery of cells or bioactive molecules.

  6. Stability testing of alginate-chitosan films.

    PubMed

    Rabisková, Miloslava; Dvorácková, Katerina; Kofronvá, Lenka

    2012-02-01

    Pellets containing rutin prepared by the extrusion/spheronization method were coated with sodium alginate-chitosan film. Important quality parameters in the pellets before coating were determined, and after coating the dissolution profiles of the drug were evaluated in dissolution media of the pH corresponding to the conditions in the gastrointestinal tract. Samples of coated pellets were located in the boxes for stability testing under different conditions, i.e. 25 degrees C and 60% of relative humidity (RH); 30 degrees C and 65% RH and 40 degrees C and 75% RH. After 1, 3, 6, 9 and 12 months (or 1, 3 and 6 months), the dissolution test was repeated and compared with the original profiles using similarity factors. All similarity factor values above 50 indicate excellent stability of alginate-chitosan films.

  7. Effect of sodium-alginate and laminaran on Salmonella Typhimurium infection in human enterocyte-like HT-29-Luc cells and BALB/c mice.

    PubMed

    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.

  8. Prosopis alba exudate gum as excipient for improving fish oil stability in alginate-chitosan beads.

    PubMed

    Vasile, Franco Emanuel; Romero, Ana María; Judis, María Alicia; Mazzobre, María Florencia

    2016-01-01

    The aim of the present work was to employ an exudate gum obtained from a South American wild tree (Prosopis alba), as wall material component to enhance the oxidative stability of fish oil encapsulated in alginate-chitosan beads. For this purpose, beads were vacuum-dried and stored under controlled conditions. Oxidation products, fatty acid profiles and lipid health indices were measured during storage. Alginate-chitosan interactions and the effect of gum were manifested in the FT-IR spectra. The inclusion of the gum in the gelation media allowed decreasing the oxidative damage during storage in comparison to the free oil and alginate-chitosan beads. The gum also improved wall material properties, providing higher oil retention during the drying step and subsequent storage. Fatty acids quality and lipid health indices were widely preserved in beads containing the gum. Present results showed a positive influence of the gum on oil encapsulation and stability, being the main mechanism attributed to a physical barrier effect.

  9. Biocompatibility of microcapsules for cell immobilization elaborated with different type of alginates.

    PubMed

    Orive, G; Ponce, S; Hernández, R M; Gascón, A R; Igartua, M; Pedraz, J L

    2002-09-01

    The biocompatibility of alginate-PLL-alginate (APA) microcapsules has been evaluated with respect to impurity levels. The impurity content of three different alginates (a raw high M-alginate, a raw high G-alginate and a purified high G-alginate) has been determined and the in vivo antigenic response of APA beads made with each alginate assessed. Results show that purification of the alginate not only reduces the total amount of impurities (63% less in polyphenols, 91.45% less in endotoxins and 68.5% less in protein in relation to raw high M-alginate), but also avoids an antibody response when microcapsules of this material are implanted in mice. In contrast, raw alginates produced a detectable antibody response though the differences in their impurity content. Consequently, this work revealed that purity of the alginate rather than their chemical composition, is probably of greater importance in determining microcapsule biocompatibility.

  10. Comparative study of calcium alginate, activated carbon, and their composite beads on methylene blue adsorption.

    PubMed

    Hassan, A F; Abdel-Mohsen, A M; Fouda, Moustafa M G

    2014-02-15

    Three adsorbents, calcium alginate beads (AB), sodium hydroxide activated carbon based coconut shells (C), and calcium alginate/activated carbon composite beads (ACB) were prepared. Their textural properties were characterized by N2-adsorption at -196°C and scanning electron microscopy. The porosity, surface area and total pore volume of C>ACB>AB, but AB adsorbent was more acidic function groups more than the other adsorbents. Adsorption experiments were conducted to examine the effects of adsorbent dosage, pH, time, temperature and initial concentration of methylene blue. Methylene blue adsorption on C, AB and ACB was observed at pH>6 to avoid the competition of H(+). The amount of dye adsorbed increases as the adsorbent dosage increase. Adsorption of dye follows pseudo-second order mechanism. Thermodynamic studies show spontaneous and endothermic nature of the overall adsorption process.

  11. Thallium(I) sorption using Prussian blue immobilized in alginate capsules.

    PubMed

    Vincent, Thierry; Taulemesse, Jean-Marie; Dauvergne, Agnès; Chanut, Thomas; Testa, Flaviano; Guibal, Eric

    2014-01-01

    Prussian blue (PB) was immobilized in alginate capsules. The composite sorbent was used for the recovery of Tl(I) ions from slightly acidic solutions: optimum pH being close to 4. The sorption isotherm can be described by the bi-site Langmuir sorption isotherm. This means that the metal ion can be bound through two different sorption sites: one having a strong affinity for Tl(I) (probably PB), the other having a lower affinity (probably the encapsulating material). The kinetics are described by either the pseudo-second order rate equation or the Crank's equation (resistance to intraparticle diffusion). The ionic strength (increased by addition of NaCl, KCl or CaCl₂) slightly decreased sorption capacity. The SEM-EDX analysis of PB-alginate capsules (before and after Tl(I) sorption) shows that the PB is homogeneously distributed in the capsules and that all reactive groups remain available for metal binding.

  12. Effect of hemostatic agents on properties of gelatin-alginate soft tissue adhesives.

    PubMed

    Pinkas, Oded; Zilberman, Meital

    2014-01-01

    Lacerations and traumatic wounds are considered to be among the most prevalent scenarios encountered in hospitals and emergency rooms. Reattachment of the lacerated soft tissue edges is traditionally performed using sutures. Use of tissue adhesives, i.e. substances that have the ability to firmly attach lacerated tissues back together, has raised interest as an alternative, due to several advantages. Novel tissue adhesives based on the natural polymers gelatin and alginate, and cross-linked by carbodiimide (EDC), were recently developed by our research group. In the current research, two types of hemostatic agents, tranexamic acid and kaolin, were loaded into our gelatin-alginate bioadhesive, in order to improve the adhesion abilities in the hemorrhagic environment of the wound. Their effects on the ex vivo adherence properties, physical properties, and biocompatibility were investigated. Incorporation of kaolin significantly improved the ex vivo bonding strength of the gelatin-alginate-EDC bioadhesives through a combination of three physical mechanisms and decreased the swelling ratio without affecting weight loss. In contradiction, incorporation of tranexamic acid into the bioadhesive formulation resulted in a lower ex vivo bonding strength and a higher swelling ratio and weight loss, probably due to reduced efficiency of the cross-linking reaction between the molecules of the natural polymers and the cross-linking agent EDC. The hemostatic agent-loaded bioadhesives showed good biocompatibility when tested in vitro on fibroblast cells. This research clearly shows that the incorporation of kaolin in our gelatin-alginate tissue adhesives may be a very promising novel approach for improving the bonding strength and physical properties of the tissue adhesives for use in hemorrhagic environments.

  13. Catalytic Mechanism and Mode of Action of the Periplasmic Alginate Epimerase AlgG*

    PubMed Central

    Wolfram, Francis; Kitova, Elena N.; Robinson, Howard; Walvoort, Marthe T. C.; Codée, Jeroen D. C.; Klassen, John S.; Howell, P. Lynne

    2014-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen that forms chronic biofilm infections in the lungs of cystic fibrosis patients. A major component of the biofilm during these infections is the exopolysaccharide alginate, which is synthesized at the inner membrane as a homopolymer of 1–4-linked β-d-mannuronate. As the polymer passages through the periplasm, 22–44% of the mannuronate residues are converted to α-l-guluronate by the C5-epimerase AlgG to produce a polymer of alternating β-d-mannuronate and α-l-guluronate blocks and stretches of polymannuronate. To understand the molecular basis of alginate epimerization, the structure of Pseudomonas syringae AlgG has been determined at 2.1-Å resolution, and the protein was functionally characterized. The structure reveals that AlgG is a long right-handed parallel β-helix with an elaborate lid structure. Functional analysis of AlgG mutants suggests that His319 acts as the catalytic base and that Arg345 neutralizes the acidic group during the epimerase reaction. Water is the likely catalytic acid. Electrostatic surface potential and residue conservation analyses in conjunction with activity and substrate docking studies suggest that a conserved electropositive groove facilitates polymannuronate binding and contains at least nine substrate binding subsites. These subsites likely align the polymer in the correct register for catalysis to occur. The presence of multiple subsites, the electropositive groove, and the non-random distribution of guluronate in the alginate polymer suggest that AlgG is a processive enzyme. Moreover, comparison of AlgG and the extracellular alginate epimerase AlgE4 of Azotobacter vinelandii provides a structural rationale for the differences in their Ca2+ dependence. PMID:24398681

  14. Catalytic mechanism and mode of action of the periplasmic alginate epimerase AlgG.

    PubMed

    Wolfram, Francis; Kitova, Elena N; Robinson, Howard; Walvoort, Marthe T C; Codée, Jeroen D C; Klassen, John S; Howell, P Lynne

    2014-02-28

    Pseudomonas aeruginosa is an opportunistic pathogen that forms chronic biofilm infections in the lungs of cystic fibrosis patients. A major component of the biofilm during these infections is the exopolysaccharide alginate, which is synthesized at the inner membrane as a homopolymer of 1-4-linked β-D-mannuronate. As the polymer passages through the periplasm, 22-44% of the mannuronate residues are converted to α-L-guluronate by the C5-epimerase AlgG to produce a polymer of alternating β-D-mannuronate and α-L-guluronate blocks and stretches of polymannuronate. To understand the molecular basis of alginate epimerization, the structure of Pseudomonas syringae AlgG has been determined at 2.1-Å resolution, and the protein was functionally characterized. The structure reveals that AlgG is a long right-handed parallel β-helix with an elaborate lid structure. Functional analysis of AlgG mutants suggests that His(319) acts as the catalytic base and that Arg(345) neutralizes the acidic group during the epimerase reaction. Water is the likely catalytic acid. Electrostatic surface potential and residue conservation analyses in conjunction with activity and substrate docking studies suggest that a conserved electropositive groove facilitates polymannuronate binding and contains at least nine substrate binding subsites. These subsites likely align the polymer in the correct register for catalysis to occur. The presence of multiple subsites, the electropositive groove, and the non-random distribution of guluronate in the alginate polymer suggest that AlgG is a processive enzyme. Moreover, comparison of AlgG and the extracellular alginate epimerase AlgE4 of Azotobacter vinelandii provides a structural rationale for the differences in their Ca(2+) dependence.

  15. The cytochrome P450 2AA gene cluster in zebrafish (Danio rerio): Expression of CYP2AA1 and CYP2AA2 and response to phenobarbital-type inducers

    SciTech Connect

    Kubota, Akira; Bainy, Afonso C.D.; Woodin, Bruce R.; Goldstone, Jared V.; Stegeman, John J.

    2013-10-01

    The cytochrome P450 (CYP) 2 gene family is the largest and most diverse CYP gene family in vertebrates. In zebrafish, we have identified 10 genes in a new subfamily, CYP2AA, which does not show orthology to any human or other mammalian CYP genes. Here we report evolutionary and structural relationships of the 10 CYP2AA genes and expression of the first two genes, CYP2AA1 and CYP2AA2. Parsimony reconstruction of the tandem duplication pattern for the CYP2AA cluster suggests that CYP2AA1, CYP2AA2 and CYP2AA3 likely arose in the earlier duplication events and thus are most diverged in function from the other CYP2AAs. On the other hand, CYP2AA8 and CYP2AA9 are genes that arose in the latest duplication event, implying functional similarity between these two CYPs. A molecular model of CYP2AA1 showing the sequence conservation across the CYP2AA cluster reveals that the regions with the highest variability within the cluster map onto CYP2AA1 near the substrate access channels, suggesting differing substrate specificities. Zebrafish CYP2AA1 transcript was expressed predominantly in the intestine, while CYP2AA2 was most highly expressed in the kidney, suggesting differing roles in physiology. In the liver CYP2AA2 expression but not that of CYP2AA1, was increased by 1,4-bis [2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) and, to a lesser extent, by phenobarbital (PB). In contrast, pregnenolone 16α-carbonitrile (PCN) increased CYP2AA1 expression, but not CYP2AA2 in the liver. The results identify a CYP2 subfamily in zebrafish that includes genes apparently induced by PB-type chemicals and PXR agonists, the first concrete in vivo evidence for a PB-type response in fish. - Highlights: • A tandemly duplicated cluster of ten CYP2AA genes was described in zebrafish. • Parsimony and duplication analyses suggest pathways to CYP2AA diversity. • Homology models reveal amino acid positions possibly related to functional diversity. • The CYP2AA locus does not share synteny with

  16. Screening of Alginate Lyase-Producing Bacteria and Optimization of Media Compositions for Extracellular Alginate Lyase Production

    PubMed Central

    Tavafi, Hadis; Abdi- Ali, Ahya A; Ghadam, Parinaz; Gharavi, Sara

    2017-01-01

    Background: Alginate is a linear polysaccharide consisting of guluronate (polyG) and mannuronate (polyM) subunits. Methods: In the initial screening of alginate-degrading bacteria from soil, 10 isolates were able to grow on minimal medium containing alginate. The optimization of cell growth and alginate lyase (algL) production was carried out by the addition of 0.8% alginate and 0.2-0.3 M NaCl to the culture medium. Of 10 isolates, one was selected based on its fast growth rate on minimal 9 medium containing 0.4% sodium alginate. The selected bacterium, identified based on morphological and biochemical characteristics, as well as 16S rDNA sequence data, was confirmed to be an isolate belonging to the genus Bacillus and designated as Bacillus sp. TAG8. Results: The results showed the ability of Bacillus sp. TAG8 in utilizing alginate as a sole carbon source. Bacillus sp. TAG8 growth and algL production were augmented with an increase in sodium alginate concentration and also by the addition of 0.2-0.3 M NaCl. Molecular analysis of TAG8 algL gene showed 99% sequence identity with algL of Pseudomonas aeruginosa PAO1. The algL produced by Bacillus sp. TAG8 cleaved both polyM and polyG blocks in alginate molecule, as well as acetylated alginate residues, confirming the bifunctionality of the isolated lyase. Conclusion: The identification of novel algL genes from microbial communities constitutes a new approach for exploring lyases with specific activity against bacterial alginates and may thus contribute to the eradication of persistent biofilms from clinical samples. PMID:27432784

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

    PubMed Central

    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 hypothesis that the product of algG is a C5-epimerase that directly converts D-mannuronate to L-guluronate. The DNA sequence of algG was determined, and an open reading frame encoding a protein (AlgG) of approximately 60 kDa was identified. The inferred amino terminus of AlgG protein contained a putative signal sequence of 35 amino acids. Expression of algG in Escherichia coli demonstrated both 60-kDa pre-AlgG and 55-kDa mature AlgG proteins, the latter of which was localized to the periplasm. An N-terminal analysis of AlgG showed that the signal sequence was removed in the mature form. Pulse-chase experiments in both E. coli and P. aeruginosa provided evidence for conversion of the 60- to the 55-kDa size in vivo. Expression of algG from a plasmid inan algG (i.e., polymannuronate-producing) mutant of P. aeruginosa restored production of an alginate containing L-guluronate residues. The observation that AlgG is apparently processed and exported from the cytoplasm suggested that it may act as a polymer-level mannuronan C5-epimerase. An in vitro assay for mannuronan C5 epimerization was developed wherein extracts of E. coli expressing high levels of AlgG were incubated with polymannuronate. Epimerization of D-mannuronate to L-guluronate residues in the polymer was detected enzymatically, using a L-guluronate-specific alginate lyase of Klebsiella aerogenes. Epimerization was also detected in the in vitro reaction between recombinant AlgG and poly-D-mannuronate, using high

  18. Energy Landscape of Alginate-Epimerase Interactions Assessed by Optical Tweezers and Atomic Force Microscopy

    PubMed Central

    Håti, Armend Gazmeno; Aachmann, Finn Lillelund; Stokke, Bjørn Torger; Skjåk-Bræk, Gudmund; Sletmoen, Marit

    2015-01-01

    observed different affinities determined for AlgE4-polymannuronic acid (poly-M) and AlgE4-polyalternating alginate (poly-MG) macromolecular pairs these data give important contribution to the growing understanding of the mechanisms underlying the processive mode of these enzymes. PMID:26496653

  19. Fecal transmission of AA amyloidosis in the cheetah contributes to high incidence of disease.

    PubMed

    Zhang, Beiru; Une, Yumi; Fu, Xiaoying; Yan, Jingmin; Ge, FengXia; Yao, Junjie; Sawashita, Jinko; Mori, Masayuki; Tomozawa, Hiroshi; Kametani, Fuyuki; Higuchi, Keiichi

    2008-05-20

    AA amyloidosis is one of the principal causes of morbidity and mortality in captive cheetahs (Acinonyx jubatus), which are in danger of extinction, but little is known about the underlying mechanisms. Given the transmissible characteristics of AA amyloidosis, transmission between captive cheetahs may be a possible mechanism involved in the high incidence of AA amyloidosis. In this study of animals with AA amyloidosis, we found that cheetah feces contained AA amyloid fibrils that were different from those of the liver with regard to molecular weight and shape and had greater transmissibility. The infectious activity of fecal AA amyloid fibrils was reduced or abolished by the protein denaturants 6 M guanidine.HCl and formic acid or by AA immunodepletion. Thus, we propose that feces are a vehicle of transmission that may accelerate AA amyloidosis in captive cheetah populations. These results provide a pathogenesis for AA amyloidosis and suggest possible measures for rescuing cheetahs from extinction.

  20. A Controlled Drug-Delivery Experiment Using Alginate Beads

    ERIC Educational Resources Information Center

    Farrell, Stephanie; Vernengo, Jennifer

    2012-01-01

    This paper describes a simple, cost-effective experiment which introduces students to drug delivery and modeling using alginate beads. Students produce calcium alginate beads loaded with drug and measure the rate of release from the beads for systems having different stir rates, geometries, extents of cross-linking, and drug molecular weight.…

  1. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Propylene glycol alginate. 172.858 Section 172.858... CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... information required by the act: (1) The name of the additive, “propylene glycol alginate” or...

  2. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Propylene glycol alginate. 172.858 Section 172.858... CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... information required by the act: (1) The name of the additive, “propylene glycol alginate” or...

  3. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Propylene glycol alginate. 172.858 Section 172.858... CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... information required by the act: (1) The name of the additive, “propylene glycol alginate” or...

  4. Applications of Alginate-Based Bioinks in 3D Bioprinting

    PubMed Central

    Axpe, Eneko; Oyen, Michelle L.

    2016-01-01

    Three-dimensional (3D) bioprinting is on the cusp of permitting the direct fabrication of artificial living tissue. Multicellular building blocks (bioinks) are dispensed layer by layer and scaled for the target construct. However, only a few materials are able to fulfill the considerable requirements for suitable bioink formulation, a critical component of efficient 3D bioprinting. Alginate, a naturally occurring polysaccharide, is clearly the most commonly employed material in current bioinks. Here, we discuss the benefits and disadvantages of the use of alginate in 3D bioprinting by summarizing the most recent studies that used alginate for printing vascular tissue, bone and cartilage. In addition, other breakthroughs in the use of alginate in bioprinting are discussed, including strategies to improve its structural and degradation characteristics. In this review, we organize the available literature in order to inspire and accelerate novel alginate-based bioink formulations with enhanced properties for future applications in basic research, drug screening and regenerative medicine. PMID:27898010

  5. Cytochrome aa3 in Haloferax volcanii

    PubMed Central

    Tanaka, Mikiei; Ogawa, Naohide; Ihara, Kunio; Sugiyama, Yasuo; Mukohata, Yasuo

    2002-01-01

    A cytochrome in an extremely halophilic archaeon, Haloferax volcanii, was purified to homogeneity. This protein displayed a redox difference spectrum that is characteristic of a-type cytochromes and a CN− complex spectrum that indicates the presence of heme a and heme a3. This cytochrome aa3 consisted of 44- and 35-kDa subunits. The amino acid sequence of the 44-kDa subunit was similar to that of the heme-copper oxidase subunit I, and critical amino acid residues for metal binding, such as histidines, were highly conserved. The reduced cytochrome c partially purified from the bacterial membrane fraction was oxidized by the cytochrome aa3, providing physiological evidence for electron transfer from cytochrome c to cytochrome aa3 in archaea. PMID:11790755

  6. Comparison of some biochemical properties of artichoke polyphenol oxidase entrapped in alginate-carrageenan and alginate gels.

    PubMed

    Yagar, Hulya; Kocaturk, Selin

    2014-08-01

    Polyphenol oxidase (PPO, EC.1.14.18.1) isolated from artichoke (Cynara scolymus) was entrapped within alginate and alginate+ carrageenan beads, and the catecholase and cresolase activities of both entrapped enzymes were determined. Some properties of these immobilized enzymes such as optimum pH and temperature, kinetic parameters (Km and Vmax), thermal, and storage stability were determined and compared to each other. The highest catecholase activity was observed in alginate gel (370 U/g bead) while the highest cresolase activity was in alginate+ carrageenan gel (90 U/g bead). For catecholase and cresolase activities, optimum pHs of alginate and alginate+ carrageenan beads were determined to be 7.0 and 4.0, respectively. Optimum temperatures for catecholase activity were determined to be 40°C for both entrapped enzymes. These values for cresolase activity were 30°C and 20°C, respectively. Immobilized artichoke PPOs greatly preserved their thermal stability which exists anyway. The catalytic efficiency value (Vmax/Km) of the alginate beads is approximately high as two-and-a-half folds of that of alginate+κ-carrageenan beads for cresolase activity. These values were very close for catecholase activity. Immobilized beads saved their both activities after 30 days of storage at 4°C.

  7. Alginate gel-coated oil-entrapped alginate-tamarind gum-magnesium stearate buoyant beads of risperidone.

    PubMed

    Bera, Hriday; Boddupalli, Shashank; Nandikonda, Sridhar; Kumar, Sanoj; Nayak, Amit Kumar

    2015-01-01

    A novel alginate gel-coated oil-entrapped calcium-alginate-tamarind gum (TG)-magnesium stearate (MS) composite floating beads was developed for intragastric risperidone delivery with a view to improving its oral bioavailability. The TG-blended alginate core beads containing olive oil and MS as low-density materials were accomplished by ionotropic gelation technique. Effects of polymer-blend ratio (sodium alginate:TG) and crosslinker (CaCl2) concentration on drug entrapment efficiency (DEE, %) and cumulative drug release after 8 h (Q8h, %) were studied to optimize the core beads by a 3(2) factorial design. The optimized beads (F-O) exhibited DEE of 75.19±0.75% and Q8h of 78.04±0.38% with minimum errors in prediction. The alginate gel-coated optimized beads displayed superior buoyancy and sustained drug release property. The drug release profiles of the drug-loaded uncoated and coated beads were best fitted in Higuchi kinetic model with Fickian and anomalous diffusion driven mechanisms, respectively. The optimized beads yielded a notable sustained drug release profile as compared to marketed immediate release preparation. The uncoated and coated Ca-alginate-TG-MS beads were also characterized by SEM, FTIR and P-XRD analyses. Thus, the newly developed alginate-gel coated oil-entrapped alginate-TG-MS composite beads are suitable for intragastric delivery of risperidone over a prolonged period of time.

  8. Ion exchange in alginate gels--dynamic behaviour revealed by electron paramagnetic resonance.

    PubMed

    Ionita, Gabriela; Ariciu, Ana Maria; Smith, David K; Chechik, Victor

    2015-12-14

    The formation of alginate gel from low molecular weight alginate and very low molecular weight alginate in the presence of divalent cations was investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. The transition from sol to gel in the presence of divalent cations was monitored by the changes in the dynamics of spin labelled alginate. The immobilisation of the spin labelled alginate in the gel reflects the strength of interaction between the cation and alginate chain. Diffusion experiments showed that both the cation and alginate polyanion in the gel fibres can exchange with molecules in solution. In particular, we showed that dissolved alginate polyanions can replace alginates in the gel fibres, which can hence diffuse through the bulk of the gel. This illustrates the surprisingly highly dynamic nature of these gels and opens up the possibility of preparing multicomponent alginate gels via polyanion exchange process.

  9. Time-Dependent Effect of Encapsulating Alginate Hydrogel on Neurogenic Potential

    PubMed Central

    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

  10. Preparation and characterization of electrospun alginate/PLA nanofibers as tissue engineering material by emulsion eletrospinning.

    PubMed

    Xu, Weihong; Shen, Renzhe; Yan, Yurong; Gao, Jie

    2017-01-01

    Scaffolds made by biomaterials offer favorite environment for cell grow and show a wide potential application in tissue engineering. Novel biocompatibility materials polylatic acid (PLA) nanofiber membranes with favorable biocompatibility and good mechanical strength could serve as an innovative tissue engineering scaffold. Sodium alginate (SA) could be used in biomedical areas because of its anti-bacterial property, hydrophilicity and biocompatibility. In this article, we chose PLA as continuous phase and SA as dispersion phase to prepare a W/O emulsion and then electrospun it to get a SA/PLA composite nanofiber membranes. The CLSM images illustrated that the existence of SA was located on the surface of composite fibers and the FTIR results confirmed the result. A calcium ion replacement step was used as an after-treatment for SA/PLA nanofiber membranes in order to anchor the alginic ion in a form of gelated calcium alginate (CA). The single fiber tensile test shows a good mechanical property of CA/PLA nanofiber membranes, and the nanofiber membranes are beneficial for cell proliferation and differentiation owing to MTT array as well as Alizarin red S (ARS) staining test.

  11. Alginate Particles as Platform for Drug Delivery by the Oral Route: State-of-the-Art

    PubMed Central

    2014-01-01

    Pharmaceutical research and development aims to design products with ensured safety, quality, and efficacy to treat disease. To make the process more rational, coherent, efficient, and cost-effective, the field of Pharmaceutical Materials Science has emerged as the systematic study of the physicochemical properties and behavior of materials of pharmaceutical interest in relation to product performance. The oral route is the most patient preferred for drug administration. The presence of a mucus layer that covers the entire gastrointestinal tract has been exploited to expand the use of the oral route by developing a mucoadhesive drug delivery system that showed a prolonged residence time. Alginic acid and sodium and potassium alginates have emerged as one of the most extensively explored mucoadhesive biomaterials owing to very good cytocompatibility and biocompatibility, biodegradation, sol-gel transition properties, and chemical versatility that make possible further modifications to tailor their properties. The present review overviews the most relevant applications of alginate microparticles and nanoparticles for drug administration by the oral route and discusses the perspectives of this biomaterial in the future. PMID:25101184

  12. Section AA Pre2004 Fire, Section AA 2009, Section AA, South ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Section A-A Pre-2004 Fire, Section A-A 2009, Section A-A, South Elevation - Boston & Maine Railroad, Berlin Branch Bridge #148.81, Formerly spanning Moose Brook at former Boston & Maine Railroad, Gorham, Coos County, NH

  13. Dimensional changes of alginate dental impression materials.

    PubMed

    Nallamuthu, N; Braden, M; Patel, M P

    2006-12-01

    The weight loss and corresponding dimensional changes of two dental alginate impression materials have been studied. The weight loss kinetics indicate this to be a diffusion controlled process, but with a boundary condition at the surface of the concentration decreasing exponentially with time. This is in marked contrast to most desorption processes, where the surface concentration becomes instantaneously zero. The appropriate theory has been developed for an exponential boundary condition, and its predictions compared with experimental data; the agreement was satisfactory. The diffusion coefficients for two thicknesses of the same material were not identical as predicted by theory; the possible reasons for this are discussed.

  14. Hollow chitosan/alginate nanocapsules for bioactive compound delivery.

    PubMed

    Rivera, Melissa C; Pinheiro, Ana C; Bourbon, Ana I; Cerqueira, Miguel A; Vicente, António A

    2015-08-01

    This work aimed at the development of biodegradable nanocapsules as carriers of two bioactive compounds, 5-aminosalycilic acid and glycomacropeptide. Nanocapsules were produced through layer-by-layer (LbL) deposition of chitosan (CH) and alginate (ALG) layers on polystyrene nanoparticles. The bioactive compounds were incorporated on the third layer of the nanocapsules being its encapsulation efficiency and release behaviour evaluated. The LbL deposition process, stability, morphology and size of the multilayer nanocapsules were monitored by means of zeta potential and transmission electron microscopy (TEM). The bioactive compounds release from the CH/ALG nanocapsules was successfully described by a mathematical model (linear superimposition model - LSM), which allowed concluding that bioactive compounds release is due to both Brownian motion and the polymer relaxation of the CH/ALG layers. Final results demonstrated that the synthesized LbL hollow nanocapsules presented spherical morphology and a good capacity to encapsulate different bioactive compounds, being the best results obtained for the system containing 5-aminosalycilic acid (with an encapsulation efficiency of approximately 70%). CH/ALG multilayer nanocapsules could be a promising carrier of bioactive compounds for applications in food and pharmaceutical industries.

  15. Surface detail reproduction and dimensional accuracy of stone models: influence of disinfectant solutions and alginate impression materials.

    PubMed

    Guiraldo, Ricardo Danil; Borsato, Thaís Teixeira; Berger, Sandrine Bittencourt; Lopes, Murilo Baena; Gonini-Jr, Alcides; Sinhoreti, Mário Alexandre Coelho

    2012-01-01

    This study compared the surface detail reproduction and dimensional accuracy of stone models obtained from molds disinfected with 2% sodium hypochlorite, 2% chlorhexidine digluconate or 0.2% peracetic acid to models produced using molds which were not disinfected, with 3 alginate materials (Cavex ColorChange, Hydrogum 5 and Jeltrate Plus). The molds were prepared over matrix containing 20-, 50-, and 75-µm lines, performed under pressure with perforated metal tray. The molds were removed following gelation and either disinfected (using one of the solutions by spraying followed by storage in closed jars for 15 min) or not disinfected. The samples were divided into 12 groups (n=5). Molds were filled with dental gypsum Durone IV and 1 h after the start of the stone mixing the models were separated from the tray. Surface detail reproduction and dimensional accuracy were evaluated using optical microscopy on the 50-µm line with 25 mm in length, in accordance with the ISO 1563 standard. The dimensional accuracy results (%) were subjected to ANOVA. The 50 µm-line was completely reproduced by all alginate impression materials regardless of the disinfection procedure. There was no statistically significant difference in the mean values of dimensional accuracy in combinations between disinfectant procedure and alginate impression material (p=0.2130) or for independent factors. The disinfectant solutions and alginate materials used in this study are no factors of choice regarding the surface detail reproduction and dimensional accuracy of stone models.

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

    PubMed

    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.

  17. Molecular engineering of manipulated alginate-based polyurethanes.

    PubMed

    Daemi, Hamed; Barikani, Mehdi

    2014-11-04

    The novel soluble alginate-based polyurethanes in organic solvents were synthesized by the reaction of NCO-terminated prepolymers and tributylammonium alginate (TBA-Alg) for the first time. The chemical structures of synthesized polyurethanes were characterized using FTIR, (1)H NMR and TGA. The reaction completion was confirmed by disappearing of NCO band in FTIR spectra. Furthermore, a peak at 4.71 ppm and some small peaks at a range of 4.12-4.37 ppm in the (1)H NMR of alginate-based polyurethanes were assigned to the backbone of alginate. The results of both FTIR and (1)H NMR were remarkably confirmed by TGA data. The ionic nature of polyurethane backbone not only affects on thermal properties of samples, but it also changes the chemically-bonded alginate morphology. Both polyether and polyester based non-ionic polyurethanes extended by TBA-Alg illustrated the distinct alginate, whereas those ionomers extended by alginate were appeared as the continuous systems at nanoscale.

  18. Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

    PubMed

    Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

    2016-10-01

    The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (<50μm) were investigated in this work as carriers for mucosal administration of drugs. Low methoxyl pectin and κ-carrageenan were co-gelled with alginate and further dried with supercritical CO2 (sc-CO2). Spherical mesoporous aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications.

  19. Quantitative Assessment of Islets of Langerhans Encapsulated in Alginate

    PubMed Central

    Johnson, Amy S.; O'Sullivan, Esther; D'Aoust, Laura N.; Omer, Abdulkadir; Bonner-Weir, Susan; Fisher, Robert J.; Weir, Gordon C.

    2011-01-01

    Improved methods have recently been developed for assessing islet viability and quantity in human islet preparations for transplantation, and these measurements have proven useful for predicting transplantation outcome. The objectives of this study were to adapt these methods for use with microencapsulated islets, to verify that they provide meaningful quantitative measurements, and to test them with two model systems: (1) barium alginate and (2) barium alginate containing a 70% (w/v) perfluorocarbon (PFC) emulsion, which presents challenges to use of these assays and is of interest in its own right as a means for reducing oxygen supply limitations to encapsulated tissue. Mitochondrial function was assessed by oxygen consumption rate measurements, and the analysis of data was modified to account for the increased solubility of oxygen in the PFC-alginate capsules. Capsules were dissolved and tissue recovered for nuclei counting to measure the number of cells. Capsule volume was determined from alginate or PFC content and used to normalize measurements. After low oxygen culture for 2 days, islets in normal alginate lost substantial viable tissue and displayed necrotic cores, whereas most of the original oxygen consumption rate was recovered with PFC alginate, and little necrosis was observed. All nuclei were recovered with normal alginate, but some nuclei from nonrespiring cells were lost with PFC alginate. Biocompatibility tests revealed toxicity at the islet periphery associated with the lipid emulsion used to provide surfactants during the emulsification process. We conclude that these new assay methods can be applied to islets encapsulated in materials as complex as PFC-alginate. Measurements made with these materials revealed that enhancement of oxygen permeability of the encapsulating material with a concentrated PFC emulsion improves survival of encapsulated islets under hypoxic conditions, but reformulation of the PFC emulsion is needed to reduce toxicity

  20. An anomalous behavior of trypsin immobilized in alginate network.

    PubMed

    Ganachaud, Chrystelle; Bernin, Diana; Isaksson, Dan; Holmberg, Krister

    2013-05-01

    Alginate is a biopolymer used in drug formulations and for surgical purposes. In the presence of divalent cations, it forms solid gels, and such gels are of interest for immobilization of cells and enzymes. In this work, we entrapped trypsin in an alginate gel together with a known substrate, N α-benzoyl-L-arginine-4-nitroanilide hydrochloride (L-BAPNA), and in the presence or absence of D-BAPNA, which is known to be a competitive inhibitor. Interactions between alginate and the substrate as well as the enzyme were characterized with transmission electron microscopy, rheology, and nuclear magnetic resonance spectroscopy. The biocatalysis was monitored by spectrophotometry at temperatures ranging from 10 to 42 °C. It was found that at 37 and 42 °C a strong acceleration of the reaction was obtained, whereas at 10 °C and at room temperature, the presence of D-BAPNA leads to a retardation of the reaction rate. The same effect was found when the reaction was performed in a non-cross-linked alginate solution. In alginate-free buffer solution, as well as in a solution of carboxymethylcellulose, a biopolymer that resembles alginate, the normal behavior was obtained; however, with D-BAPNA acting as an inhibitor at all temperatures. A more detailed investigation of the reaction kinetics showed that at higher temperature and in the presence of alginate, the curve of initial reaction rate versus L-BAPNA concentration had a sigmoidal shape, indicating an allosteric behavior. We believe that the anomalous behavior of trypsin in the presence of alginate is due to conformational changes caused by interactions between the positively charged trypsin and the strongly negatively charged alginate.

  1. Chitosan-alginate membranes accelerate wound healing.

    PubMed

    Caetano, Guilherme Ferreira; Frade, Marco Andrey Cipriani; Andrade, Thiago Antônio Moretti; Leite, Marcel Nani; Bueno, Cecilia Zorzi; Moraes, Ângela Maria; Ribeiro-Paes, João Tadeu

    2015-07-01

    The purpose of this study was to evaluate the efficacy of chitosan-alginate membrane to accelerate wound healing in experimental cutaneous wounds. Two wounds were performed in Wistar rats by punching (1.5 cm diameter), treated with membranes moistened with saline solution (CAM group) or with saline only (SL group). After 2, 7, 14, and 21 days of surgery, five rats of each group were euthanized and reepithelialization was evaluated. The wounds/scars were harvested for histological, flow cytometry, neutrophil infiltrate, and hydroxyproline analysis. CAM group presented higher inflammatory cells recruitment as compared to SL group on 2(nd) day. On the 7(th) day, CAM group showed higher CD11b(+) level and lower of neutrophils than SL group. The CAM group presented higher CD4(+) cells influx than SL group on 2(nd) day, but it decreased during the follow up and became lower on 14(th) and 21(st) days. Higher fibroplasia was noticed on days 7 and 14 as well as higher collagenesis on 21(st) in the CAM group in comparison to SL group. CAM group showed faster reepithelialization on 7(th) day than SL group, although similar in other days. In conclusion, chitosan-alginate membrane modulated the inflammatory phase, stimulated fibroplasia and collagenesis, accelerating wound healing process in rats.

  2. Influence of the extraction-purification conditions on final properties of alginates obtained from brown algae (Macrocystis pyrifera).

    PubMed

    Gomez, César G; Pérez Lambrecht, María V; Lozano, Jorge E; Rinaudo, Marguerite; Villar, Marcelo A

    2009-05-01

    In this work, three methods (ethanol, HCl, and CaCl(2) routes) of sodium alginate extraction-purification from brown seaweeds (Macrocystis pyrifera) were used in order to study the influence of process conditions on final properties of the polymer. In the CaCl(2) route, was found that the precipitation step in presence of calcium ions followed by proton-exchange in acid medium clearly gives alginates with the lowest molecular weight and poor mechanical properties. It is well known that the acid treatment degrade the ether bonds on the polymeric chain. Ethanol route displayed the best performance, where the highest yield and rheological properties were attained with the lowest number of steps. Although the polymer I.1 showed a molar mass and polydispersity index (M(w)/M(n)) similar to those of commercial sample, its mechanical properties were lower. This performance is related to the higher content of guluronic acid in the commercial alginate, which promotes a more successful calcium chelation. Moreover, the employment of pH 4 in the acid pre-treatment improved the yield of the ethanol route, avoiding the ether linkage hydrolysis. Therefore, samples I.2 and I.3 displayed a higher M(w) and a narrower distribution of molecular weights than commercial sample, which gave a higher viscosity and better viscoelastic properties.

  3. Structural, physicochemical and antioxidant properties of sodium alginate isolated from a Tunisian brown seaweed.

    PubMed

    Sellimi, Sabrine; Younes, Islem; Ayed, Hanen Ben; Maalej, Hana; Montero, Veronique; Rinaudo, Marguerite; Dahia, Mostefa; Mechichi, Tahar; Hajji, Mohamed; Nasri, Moncef

    2015-01-01

    An original sodium alginate from Tunisian seaweed (Cystoseira barbata) was purified and characterized by circular dichroism (CD) and ATR-FTIR spectroscopies. ATR-FTIR spectrum of C. barbata sodium alginate (CBSA) showed the characteristic bands of mannuronic (M) and guluronic acids (G). The M/G ratio was estimated by CD (M/G = 0.59) indicating that CBSA was composed of 37% mannuronic acid and 63% guluronic acid. The analysis of viscosity of CBSA showed evidence of pseudoplastic fluid behaviour. The emulsifying capacity of CBSA was evaluated at different concentrations (0.25-3%), temperatures (25-100 °C) and pH (3.0-11.0). Compared to most commercial emulsifiers, the emulsion formulated by CBSA was found to be less sensitive to temperature changes and more stable at acidic pH. CBSA was examined for antioxidant properties using various antioxidant assays. CBSA exhibited important DPPH radical-scavenging activity (74% inhibition at a concentration of 0.5 mg/ml) and considerable ferric reducing potential. Effective hydroxyl-radical scavenging activity (82% at a concentration of 5 mg/ml) and potent protection activity against DNA breakage were also recorded for CBSA. However, in the linoleate-β-carotene system, CBSA exerted moderate antioxidant activity (60% at a concentration of 1.5 mg/ml). Therefore, CBSA can be used as a natural ingredient in food industry or in the pharmaceutical field.

  4. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induced P-450 mediated arachidonic acid (AA) metabolism in chick embryo liver (CEL) occurs in parenchymal cells (PC) rather than in non-parenchymal cells (NPC)

    SciTech Connect

    Paroli, L.; Rifkind, A.B. )

    1992-02-26

    TCDD induces cytochrome P-450 mediated AA metabolism in CEL and changes the dominant metabolite(s) from {omega}-OH AA to AA epoxygenase products (EETs and EET-diols). PC and NPC from CEL were separated by differential centrifugation and characterized by morphology, immunohistochemistry and P-450 mediated xenobiotic metabolism; purities were >95%. PC and NPC, from 16 day old chick embryos treated for 5 days with TCDD or vehicle alone, were cultured for 48 hr, homogenized and incubated with ({sup 14}C)-AA {plus minus} NADPH. AA products were resolved by reverse phase HPLC. The major product in control PC, {omega}-OH AA was not significantly affected by TCDD. All of the AA metabolism was NADPH dependent. Control and TCDD treated PC had the same metabolite patterns as whole liver microsomes. Neither control nor TCDD treated NPC generated P-450 AA metabolites. Also co-culturing NPC with PC did not affect AA metabolism of either cell type. The findings indicate that TCDD-induced changes in AA metabolism are retained in culture and that hepatocytes rather than NPC effect P-450 mediated AA metabolism in both control and TCDD-induced CEL.

  5. Microbial alginate dressings show improved binding capacity for pathophysiological factors in chronic wounds compared to commercial alginate dressings of marine origin.

    PubMed

    Fischer, Melissa; Gebhard, Florian; Hammer, Timo; Zurek, Christian; Meurer, Guido; Marquardt, Christoph; Hoefer, Dirk

    2017-01-01

    Marine alginates are well established in wound management. Compared with different modern wound dressings, marine alginates cannot prove superior effects on wound healing. Alginates from bacteria have never been studied for medical applications so far, although the microbial polymer raises expectations for improved binding of wound factors because of its unique O-acetylation. Due to its possible positive effects on wound healing, alginates from bacteria might be a superior future medical product for clinical use. To prove the binding capacity of microbial alginates to pathophysiological factors in chronic wounds, we processed microbial alginate fibres, produced from fermentation of the soil bacterium Azotobacter vinelandii ATCC 9046, into needle web dressings and compared them with commercial dressings made of marine alginate. Four dressings were assessed: Marine alginate dressings containing either ionic silver or zinc/manganese/calcium, and microbial alginate dressings with and without nanosilver. All dressings were tested in an in vitro approach for influence on chronic wound parameters such as elastase, matrix metalloproteases-2, tumour necrosis factor-α, interleukin-8, and free radical formation. Despite the alginate origin or addition of antimicrobials, all dressings were able to reduce the concentration of the proinflammatory cytokines TNF-α and IL-8. However, microbial alginate was found to bind considerable larger amounts of elastase and matrix metalloproteases-2 in contrast to the marine alginate dressings. The incorporation of zinc, silver or nanosilver into alginate fibres did not improve their binding capacity for proteases or cytokines. The addition of nanosilver slightly enhanced the antioxidant capacity of microbial alginate dressings, whereas the marine alginate dressing containing zinc/manganese/calcium was unable to inhibit the formation of free radicals. The enhanced binding affinity by microbial alginate of Azotobacter vinelandii to

  6. Novel Alginate Lyase (Aly5) from a Polysaccharide-Degrading Marine Bacterium, Flammeovirga sp. Strain MY04: Effects of Module Truncation on Biochemical Characteristics, Alginate Degradation Patterns, and Oligosaccharide-Yielding Properties

    PubMed Central

    Han, Wenjun; Gu, Jingyan; Cheng, Yuanyuan; Liu, Huihui; Li, Yuezhong

    2015-01-01

    Alginate lyases are important tools for oligosaccharide preparation, medical treatment, and energy bioconversion. Numerous alginate lyases have been elucidated. However, relatively little is known about their substrate degradation patterns and product-yielding properties, which is a limit to wider enzymatic applications and further enzyme improvements. Herein, we report the characterization and module truncation of Aly5, the first alginate lyase obtained from the polysaccharide-degrading bacterium Flammeovirga. Aly5 is a 566-amino-acid protein and belongs to a novel branch of the polysaccharide lyase 7 (PL7) superfamily. The protein rAly5 is an endolytic enzyme of alginate and associated oligosaccharides. It prefers guluronate (G) to mannuronate (M). Its smallest substrate is an unsaturated pentasaccharide, and its minimum product is an unsaturated disaccharide. The final alginate digests contain unsaturated oligosaccharides that generally range from disaccharides to heptasaccharides, with the tetrasaccharide fraction constituting the highest mass concentration. The disaccharide products are identified as ΔG units. While interestingly, the tri- and tetrasaccharide fractions each contain higher proportions of ΔG to ΔM ends, the larger final products contain only ΔM ends, which constitute a novel oligosaccharide-yielding property of guluronate lyases. The deletion of the noncatalytic region of Aly5 does not alter its M/G preference but significantly decreases the enzymatic activity and enzyme stability. Notably, the truncated protein accumulates large final oligosaccharide products but yields fewer small final products than Aly5, which are codetermined by its M/G preference to and size enlargement of degradable oligosaccharides. This study provides novel enzymatic properties and catalytic mechanisms of a guluronate lyase for potential uses and improvements. PMID:26519393

  7. Novel Alginate Lyase (Aly5) from a Polysaccharide-Degrading Marine Bacterium, Flammeovirga sp. Strain MY04: Effects of Module Truncation on Biochemical Characteristics, Alginate Degradation Patterns, and Oligosaccharide-Yielding Properties.

    PubMed

    Han, Wenjun; Gu, Jingyan; Cheng, Yuanyuan; Liu, Huihui; Li, Yuezhong; Li, Fuchuan

    2015-10-30

    Alginate lyases are important tools for oligosaccharide preparation, medical treatment, and energy bioconversion. Numerous alginate lyases have been elucidated. However, relatively little is known about their substrate degradation patterns and product-yielding properties, which is a limit to wider enzymatic applications and further enzyme improvements. Herein, we report the characterization and module truncation of Aly5, the first alginate lyase obtained from the polysaccharide-degrading bacterium Flammeovirga. Aly5 is a 566-amino-acid protein and belongs to a novel branch of the polysaccharide lyase 7 (PL7) superfamily. The protein rAly5 is an endolytic enzyme of alginate and associated oligosaccharides. It prefers guluronate (G) to mannuronate (M). Its smallest substrate is an unsaturated pentasaccharide, and its minimum product is an unsaturated disaccharide. The final alginate digests contain unsaturated oligosaccharides that generally range from disaccharides to heptasaccharides, with the tetrasaccharide fraction constituting the highest mass concentration. The disaccharide products are identified as ΔG units. While interestingly, the tri- and tetrasaccharide fractions each contain higher proportions of ΔG to ΔM ends, the larger final products contain only ΔM ends, which constitute a novel oligosaccharide-yielding property of guluronate lyases. The deletion of the noncatalytic region of Aly5 does not alter its M/G preference but significantly decreases the enzymatic activity and enzyme stability. Notably, the truncated protein accumulates large final oligosaccharide products but yields fewer small final products than Aly5, which are codetermined by its M/G preference to and size enlargement of degradable oligosaccharides. This study provides novel enzymatic properties and catalytic mechanisms of a guluronate lyase for potential uses and improvements.

  8. Alginate synthesis in Pseudomonas aeruginosa: the role of AlgL (alginate lyase) and AlgX.

    PubMed Central

    Monday, S R; Schiller, N L

    1996-01-01

    Previous studies localized an alginate lyase gene (algL) within the alginate biosynthetic gene cluster at 34 min on the Pseudomonas aeruginosa chromosome. Insertion of a Tn501 polar transposon in a gene (algX) directly upstream of algL in mucoid P. aeruginosa FRD1 inactivated expression of algX, algL, and other downstream genes, including algA. This strain is phenotypically nonmucoid; however, alginate production could be restored by complementation in trans with a plasmid carrying all of the genes inactivated by the insertion, including algL and algX. Alginate production was also recovered when a merodiploid that generated a complete alginate gene cluster on the chromosome was constructed. However, alginate production by merodiploids formed in the algX::Tn501 mutant using an alginate cluster with an algL deletion was not restored to wild-type levels unless algL was provided on a plasmid in trans. In addition, complementation studies of Tn501 mutants using plasmids containing specific deletions in either algL or algX revealed that both genes were required to restore the mucoid phenotype. Escherichia coli strains which expressed algX produced a unique protein of approximately 53 kDa, consistent with the gene product predicted from the DNA sequencing data. These studies demonstrate that AlgX, whose biochemical function remains to be defined, and AlgL, which has alginate lyase activity, are both involved in alginate production by P. aeruginosa. PMID:8550492

  9. The 9aaTAD Transactivation Domains: From Gal4 to p53

    PubMed Central

    Havelka, Marek; Rezacova, Martina

    2016-01-01

    The family of the Nine amino acid Transactivation Domain, 9aaTAD family, comprises currently over 40 members. The 9aaTAD domains are universally recognized by the transcriptional machinery from yeast to man. We had identified the 9aaTAD domains in the p53, Msn2, Pdr1 and B42 activators by our prediction algorithm. In this study, their competence to activate transcription as small peptides was proven. Not surprisingly, we elicited immense 9aaTAD divergence in hundreds of identified orthologs and numerous examples of the 9aaTAD species' convergence. We found unforeseen similarity of the mammalian p53 with yeast Gal4 9aaTAD domains. Furthermore, we identified artificial 9aaTAD domains generated accidentally by others. From an evolutionary perspective, the observed easiness to generate 9aaTAD transactivation domains indicates the natural advantage for spontaneous generation of transcription factors from DNA binding precursors. PMID:27618436

  10. Bone regeneration potential of stem cells derived from periodontal ligament or gingival tissue sources encapsulated in RGD-modified alginate scaffold.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H; Shi, Songtao

    2014-02-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications.

  11. Evaluation of the factors influencing the resultant diameter of the electrospun gelatin/sodium alginate nanofibers via Box-Behnken design.

    PubMed

    Gönen, Seza Özge; Erol Taygun, Melek; Küçükbayrak, Sadriye

    2016-01-01

    This article presented a study on the effects of solution properties (i.e., gelatin concentration, alginate concentration, content of alginate solution in the blend solution, and content of acetic acid in the solvent of gelatin solution) on the average diameter of electrospun gelatin/sodium alginate nanofibers, as well as its standard deviation. For this purpose, blend solutions of two natural polymers (gelatin and sodium alginate) were prepared both in the absence and presence of ethanol. Response surface methodology based on a three-level, four-variable Box-Benkhen design was employed to define quadratic relationships between the responses and the solution properties. The individual and interactive effects of the solution properties were determined. Moreover, the adequacy of the models was verified by the validation experiments. Results showed that the average diameters of the resultant nanofibers were 68-166 nm and 90-155 nm in the absence and presence of ethanol, respectively. The experimental results were in good agreement with the predicted response values. Hence, this study provides an overview on the fabrication of gelatin/sodium alginate nanofibers with targeted diameter, which may have potential to be used in the field of tissue engineering.

  12. Degradation potential of protocatechuate 3,4-dioxygenase from crude extract of Stenotrophomonas maltophilia strain KB2 immobilized in calcium alginate hydrogels and on glyoxyl agarose.

    PubMed

    Guzik, Urszula; Hupert-Kocurek, Katarzyna; Krysiak, Marta; Wojcieszyńska, Danuta

    2014-01-01

    Microbial intradiol dioxygenases have been shown to have a great potential for bioremediation; however, their structure is sensitive to various environmental and chemical agents. Immobilization techniques allow for the improvement of enzyme properties. This is the first report on use of glyoxyl agarose and calcium alginate as matrixes for the immobilization of protocatechuate 3,4-dioxygenase. Multipoint attachment of the enzyme to the carrier caused maintenance of its initial activity during the 21 days. Immobilization of dioxygenase in calcium alginate or on glyoxyl agarose resulted in decrease in the optimum temperature by 5 °C and 10 °C, respectively. Entrapment of the enzyme in alginate gel shifted its optimum pH towards high-alkaline pH while immobilization of the enzyme on glyoxyl agarose did not influence pH profile of the enzyme. Protocatechuate 3,4-dioygenase immobilized in calcium alginate showed increased activity towards 2,5-dihydroxybenzoate, caffeic acid, 2,3-dihydroxybenzoate, and 3,5-dihydroxybenzoate. Slightly lower activity of the enzyme was observed after its immobilization on glyoxyl agarose. Entrapment of the enzyme in alginate gel protected it against chelators and aliphatic alcohols while its immobilization on glyoxyl agarose enhanced enzyme resistance to inactivation by metal ions.

  13. The AAS Workforce Survey

    NASA Astrophysics Data System (ADS)

    Postman, Marc; Norman, D. J.; Evans, N. R.; Ivie, R.

    2014-01-01

    The AAS Demographics Committee, on behalf of the AAS, was tasked with initiating a biennial survey to improve the Society's ability to serve its members and to inform the community about changes in the community's demographics. A survey, based in part on similar surveys for other scientific societies, was developed in the summer of 2012 and was publicly launched in January 2013. The survey randomly targeted 2500 astronomers who are members of the AAS. The survey was closed 4 months later (April 2013). The response rate was excellent - 63% (1583 people) completed the survey. I will summarize the results from this survey, highlighting key results and plans for their broad dissemination.

  14. Mechanical and microstructural properties of "wet" alginate and composite films containing various carbohydrates.

    PubMed

    Harper, B Allison; Barbut, Shai; Smith, Alexandra; Marcone, Massimo F

    2015-01-01

    Composite "wet" alginate films were manufactured from alginate-carbohydrate solutions containing 5% alginate and 0.25% pectin, carrageenan (kappa or iota), potato starch (modified or unmodified), gellan gum, or cellulose (extracted or commercial). The "wet" alginate films were used as a model to understand co-extruded alginate sausage casings that are currently being used by several sausage manufacturers. The mechanical, optical, and microstructural properties of the calcium cross-linked composite films were explored. In addition, the water holding capacity and textural profile analysis properties of the alginate-carbohydrate gels were studied. The results indicate that the mechanical properties of "wet" alginate films/casings can be modified by adding various carbohydrates to them. Alginate films with pectin, carrageenan, and modified potato starch had significantly (P < 0.05) greater elongation values than pure alginate films. The alginate-pectin films also had greater (P < 0.05) tensile strengths than the pure alginate films. Alginate films with extracted cellulose, commercial cellulose, and modified potato starch had lower (P < 0.05) puncture force, distance, and work values than the alginate control films. Transmission electron microscopy images showed a very uniform alginate network in the control films. Several large cellulose fibers were visible in the films with extracted cellulose, while the cellulose fibers in the films with commercial cellulose were difficult to distinguish. Despite these apparent differences in cellulose fiber length, the 2 cellulose films had similar puncture and tensile properties.

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

    NASA Astrophysics Data System (ADS)

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

    PubMed Central

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

    2016-01-01

    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. PMID:27578567

  17. Molecular and biopharmaceutical investigation of alginate-inulin synbiotic co-encapsulation of probiotic to target the colon.

    PubMed

    Atia, Abdelbasset; Gomma, Ahmed I; Fliss, Ismail; Beyssac, Eric; Garrait, Ghiselain; Subirade, Muriel

    2017-03-28

    Colon targeting, as a site-specific delivery for oral formulation, remains a major challenge, especially for sensitive bioactive components such as therapeutic forms of phages, live attenuated virus, and prebiotics-probiotics association. Synbiotics could be used to protect encapsulated probiotics during the gastrointestinal tract and control their release in the colon. To achieve these goals, effective prebiotics such as inulin could be combined with alginate-the most exploited polymer used for probiotic encapsulation-in the form of beads. This work aimed to study the biopharmaceutical behavior of alginate beads (A) and inulin-Alginate beads of different inulin concentrations (5 or 20%) in 2% alginate (AI5, AI20). Beads were loaded with three probiotic strains (Pediococcus acidilactici Ul5, Lactobacillus reuteri and Lactobacillus salivarius). Dissolution of beads was studied by USP4 under conditions simulating the gastrointestinal condition. The survival rates of the bacterial strains were measured by a specific qPCR bacterial count. Mucoadhesiveness of beads was studied by an ex-vivo method using intestinal mucosa. To understand the behavior of each formulation, the ultrastructure of the polymeric network was studied using scanning electron microscopy (SEM). Molecular interactions between alginate and inulin were studied by Fourier transform infrared spectroscopy (FTIR). Dissolution results suggested that the presence of inulin in beads provided more protection for the tested bacterial strains against the acidic pH. AI5 was the most effective formulation to deliver probiotics to the colon simulation conditions. FTIR and SEM investigations explained the differences in behavior of each formula. The developed symbiotic form provided a promising matrix for the development of colonic controlled release systems.

  18. Fabrication of homogeneously cross-linked, functional alginate microcapsules validated by NMR-, CLSM- and AFM-imaging.

    PubMed

    Zimmermann, H; Hillgärtner, M; Manz, B; Feilen, P; Brunnenmeier, F; Leinfelder, U; Weber, M; Cramer, H; Schneider, S; Hendrich, C; Volke, F; Zimmermann, U

    2003-05-01

    Cross-linked alginate microcapsules of sufficient mechanical strength can immunoisolate cells for the long-term treatment of hormone and other deficiency diseases in human beings. However, gelation of alginate by external Ba(2+) (or other divalent cations) produces non-homogeneous cross-linking of the polymeric mannuronic (M) and guluronic (G) acid chains. The stability of such microcapsules is rather limited. Here, we show that homogeneous cross-linking can be achieved by injecting BaCl(2) crystals into alginate droplets before they come into contact with external BaCl(2). The high effectiveness of this crystal gun method is demonstrated by confocal laser scanning microscopy and by advanced nuclear magnetic resonance imaging. Both techniques gave clear-cut evidence that homogeneous cross-linkage throughout the microcapsule is only obtained with simultaneous internal and external gelation. Atomic force microscopy showed a very smooth surface topography for microcapsules made by the crystal gun method, provided that excess Ba(2+) ions were removed immediately after gelation. In vitro experiments showed greatly suppressed swelling for crystal gun microcapsules. Even alginate extracted from Lessonia nigrescens (highly biocompatible) yielded microcapsules with long-term mechanical stability not hitherto possible. Encapsulation of rat islets, human monoclonal antibodies secreting hybridoma cells and murine mesenchymal stem cells transfected with cDNA encoding for bone morphogenetic protein (BMP-4) revealed that injection of BaCl(2) crystals has no adverse side effects on cell viability and function. However, the release of low-molecular weight factors (such as insulin) may be delayed when using alginate concentrations in the usual range.

  19. AAS 228: Welcome!

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-06-01

    Greetings from the 228th American Astronomical Society meeting in San Diego, California! This week, along with a team of fellow authorsfrom astrobites, Iwill bewritingupdates on selectedevents at themeeting and posting twiceeach day. You can follow along here or atastrobites.com, or catch ourlive-tweeted updates from the@astrobites Twitter account. The usual posting schedule for AAS Nova will resumenext week.If youre at the meeting, come stop by the AAS booth (Booth #211-213) to learn about the newly-announced partnership between AAS and astrobites and pick up some swag.And dont forget to visit the IOP booth in the Exhibit Hall (Booth #223) to learn more about the new corridors for AAS Journals and to pick up a badge pin to representyour corridor!

  20. AAS 227: Welcome!

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-01-01

    Greetings from the 227th American Astronomical Society meeting in Kissimmee, Florida! This week, along with several fellow authors from astrobites, Iwill bewritingupdates on selectedevents at themeeting and posting at the end of each day. You can follow along here or atastrobites.com, or catch ourlive-tweeted updates from the@astrobites Twitter account. The usual posting schedule for AAS Nova will resumenext week.If youre an author or referee (or plan to be!) and youre here at the meeting, consider joining us at our Author and Referee Workshop on Wednesday in the Tallahassee room, where well be sharingsome of the exciting new features of the AAS journals. You can drop intoeither of the two-hour sessions(10 AM 12 PM or 1 PM 3 PM), and there will be afree buffet lunch at noon.Heres the agenda:Morning SessionTopic Speaker10:00 am 10:05 amIntroductionsJulie Steffen10:05 am 10:35 amChanges at AAS Journals; How to Be a Successful AAS AuthorEthan Vishniac10:35 am 11:00 amThe Peer Review ProcessButler Burton11:00 am 11:15 amAAS Nova: Sharing AAS Authors Research with the Broader CommunitySusanna Kohler11:15 am 11:30 amFixing Software and Instrumentation Publishing: New Paper Styles in AAS JournalsChris Lintott11:30 am 11:45 amMaking Article Writing Easier with the New AASTeX v6.0Greg Schwarz11:45 am 12:00 pmBringing JavaScript and Interactivity to Your AAS Journal FiguresGus MuenchLunch SessionTopic Speaker12:00 pm 12:15 pmUnified Astronomy ThesaurusKatie Frey12:15 pm 12:30 pmAAS/ADS ORCID Integration ToolAlberto Accomazzi12:30 pm 12:45 pmWorldWide Telescope and Video AbstractsJosh Peek12:45 pm 01:00 pmArizona Astronomical Data Hub (AADH)Bryan HeidornAfternoon SessionTopic Speaker01:00 pm 01:05 pmIntroductionsJulie Steffen01:05 pm 01:35 pmChanges at AAS Journals; How to Be a Successful AAS AuthorEthan Vishniac01:35 pm 02:00 pmThe Peer Review ProcessButler Burton02:00 pm 02:15 pmAAS Nova: Sharing AAS Authors Research with the Broader CommunitySusanna Kohler02:15 pm 02:30 pm

  1. Volatile metabolites produced from agro-industrial wastes by Na-alginate entrapped Kluyveromyces marxianus.

    PubMed

    Güneşer, Onur; Karagül-Yüceer, Yonca; Wilkowska, Agnieszka; Kregiel, Dorota

    The aim of this study was to evaluate the effects of alginate entrapment on fermentation metabolites of Kluyveromyces marxianus grown in agrowastes that served as the liquid culture media. K. marxianus cells entrapped in Na-alginate were prepared using the traditional liquid-droplet-forming method. Whey and pomaces from processed tomatoes, peppers, and grapes were used as the culture media. The changes in the concentrations of sugar, alcohol, organic acids, and flavor compounds were analyzed using gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC). Both free and entrapped, K. marxianus were used individually to metabolize sugars, organic acids, alcohols, and flavor compounds in the tomato, pepper, grape, and acid whey based media. Marked changes in the fermentation behaviors of entrapped and free K. marxianus were observed in each culture. A 1.45-log increase was observed in the cell numbers of free K. marxianus during fermentation. On the contrary, the cell numbers of entrapped K. marxianus remained the same. Both free and entrapped K. marxianus brought about the fermentation of sugars such as glucose, fructose, and lactose in the agrowaste cultures. The highest volume of ethanol was produced by K. marxianus in the whey based media. The concentrations of flavor compounds such as ethyl acetate, isoamyl alcohol, isoamyl acetate, 2-phenylethyl isobutyrate, phenylethyl acetate, and phenylethyl alcohol were higher in fermented agrowaste based media compared to the control.

  2. Nanocellulose-alginate hydrogel for cell encapsulation.

    PubMed

    Park, Minsung; Lee, Dajung; Hyun, Jinho

    2015-02-13

    TEMPO-oxidized bacterial cellulose (TOBC)-sodium alginate (SA) composites were prepared to improve the properties of hydrogel for cell encapsulation. TOBC fibers were obtained using a TEMPO/NaBr/NaClO system at pH 10 and room temperature. The fibrillated TOBCs mixed with SA were cross-linked in the presence of Ca(2+) solution to form hydrogel composites. The compression strength and chemical stability of the TOBC/SA composites were increased compared with the SA hydrogel, which indicated that TOBC performed an important function in enhancing the structural, mechanical and chemical stability of the composites. Cells were successfully encapsulated in the TOBC/SA composites, and the viability of cells was investigated. TOBC/SA composites can be a potential candidate for cell encapsulation engineering.

  3. Sodium alginate decreases the permeability of intestinal mucus.

    PubMed

    Mackie, Alan R; Macierzanka, Adam; Aarak, Kristi; Rigby, Neil M; Parker, Roger; Channell, Guy A; Harding, Stephen E; Bajka, Balazs H

    2016-01-01

    In the small intestine the nature of the environment leads to a highly heterogeneous mucus layer primarily composed of the MUC2 mucin. We set out to investigate whether the soluble dietary fibre sodium alginate could alter the permeability of the mucus layer. The alginate was shown to freely diffuse into the mucus and to have minimal effect on the bulk rheology when added at concentrations below 0.1%. Despite this lack of interaction between the mucin and alginate, the addition of alginate had a marked effect on the diffusion of 500 nm probe particles, which decreased as a function of increasing alginate concentration. Finally, we passed a protein stabilised emulsion through a simulation of oral, gastric and small intestinal digestion. We subsequently showed that the addition of 0.1% alginate to porcine intestinal mucus decreased the diffusion of fluorescently labelled lipid present in the emulsion digesta. This reduction may be sufficient to reduce problems associated with high rates of lipid absorption such as hyperlipidaemia.

  4. Sodium alginate decreases the permeability of intestinal mucus

    PubMed Central

    Mackie, Alan R.; Macierzanka, Adam; Aarak, Kristi; Rigby, Neil M.; Parker, Roger; Channell, Guy A.; Harding, Stephen E.; Bajka, Balazs H.

    2016-01-01

    In the small intestine the nature of the environment leads to a highly heterogeneous mucus layer primarily composed of the MUC2 mucin. We set out to investigate whether the soluble dietary fibre sodium alginate could alter the permeability of the mucus layer. The alginate was shown to freely diffuse into the mucus and to have minimal effect on the bulk rheology when added at concentrations below 0.1%. Despite this lack of interaction between the mucin and alginate, the addition of alginate had a marked effect on the diffusion of 500 nm probe particles, which decreased as a function of increasing alginate concentration. Finally, we passed a protein stabilised emulsion through a simulation of oral, gastric and small intestinal digestion. We subsequently showed that the addition of 0.1% alginate to porcine intestinal mucus decreased the diffusion of fluorescently labelled lipid present in the emulsion digesta. This reduction may be sufficient to reduce problems associated with high rates of lipid absorption such as hyperlipidaemia. PMID:26726279

  5. Empirical study of alginate impression materials by customized proportioning system

    PubMed Central

    2016-01-01

    PURPOSE Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. MATERIALS AND METHODS The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. RESULTS No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. CONCLUSION It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit. PMID:27826387

  6. Smart designing of new hybrid materials based on brushite-alginate and monetite-alginate microspheres: bio-inspired for sequential nucleation and growth.

    PubMed

    Amer, Walid; Abdelouahdi, Karima; Ramananarivo, Hugo Ronald; Fihri, Aziz; El Achaby, Mounir; Zahouily, Mohamed; Barakat, Abdellatif; Djessas, Kamal; Clark, James; Solhy, Abderrahim

    2014-02-01

    In this report new hybrid materials based on brushite-alginate and monetite-alginate were prepared by self-assembling alginate chains and phosphate source ions via a gelation process with calcium ions. The alginate served as nanoreactor for nucleation and growth of brushite or/and monetite due to its gelling and swelling properties. The alginate gel framework, the crystalline phase and morphology of formed hybrid biomaterials were shown to be strongly dependent upon the concentration of the phosphate precursors. These materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX).

  7. Cryoprotective roles of trehalose and alginate oligosaccharides during frozen storage of peeled shrimp (Litopenaeus vannamei).

    PubMed

    Zhang, Bin; Wu, Hai-Xiao; Yang, Hui-Cheng; Xiang, Xing-Wei; Li, Hai-Bo; Deng, Shang-Gui

    2017-08-01

    Cryoprotective saccharides are widely accepted additives that reduce thawing loss, maintain texture, and retard protein denaturation in the frozen seafood. The present study aimed to investigate the roles of trehalose and alginate oligosaccharides on cryoprotection of frozen shrimp, primarily focusing on the interactions between myosin and saccharide molecules using a molecular dynamics (MD) simulation analysis. The results indicated that soaking in the trehalose and alginate oligosaccharides solutions markedly reduced thawing and cooking losses in frozen shrimp, with respective values decreasing to 6.02%, 8.14%, and 5.99%, 8.19% after 9weeks of storage, which were significantly lower than that of fresh water treatment (9.75% and 15.09%). Our assumption was that water replacement played a leading role in cryoprotection, as shown in previous experimental results and reports. Furthermore, homology modeling and MD simulations confirmed that trehalose and alginate oligosaccharides substituted the water molecules around the myosin surface by forming hydrogen bonds with polar residues of amino acids, thereby stabilizing the structures in the absence of water during frozen storage. These conditions affected the flexibility of particular amino acid residues, enhanced the residue cross correlations within the two chains of myosin, and also increased the total interaction energy between myosin and water/saccharide molecules, thereby leading to an increase in protein stability. Finally, by comparing the experimental results to that of MD simulation, significant positive correlation existed between saccharides and the stabilization of myosin in shrimp muscle. The findings of the present study may help better understand the cryoprotective mechanisms of saccharides in frozen shrimp, and the two saccharides may be potentially used as alternative additives in seafood to maintain better quality during frozen storage.

  8. [Aristolochic acid nephropathy].

    PubMed

    Witkowicz, Joanna

    2009-01-01

    Aristolochic acid nephropathy is a chronic, fibrosing, interstitial nephritis caused by aristolochic acid (AA), which is a component of the plants of Aristolochiacae family. It was first reported in 1993, in Belgium as a Chinese herb nephropathy, in patients who received a slimming regimen containing AA. The term aristolochic acid nephropathy also includes Balcan endemic nephropathy and other endemic tubulointerstitial fibrosis. Moreover, AA is a human carcinogen which induces urothelial cancer. The AA-containing herbs are banned in many countries and FDA published the warnings concerning the safety of AA-containing botanical remedies in 2000. Regarding the increasing interest in herbal medicines, uncontrolled access to botanical remedies and replacement of one herb by another AA-containing compounds makes thousands of people all around the world at risk of this grave disease.

  9. Bioactive apatite incorporated alginate microspheres with sustained drug-delivery for bone regeneration application.

    PubMed

    Li, Haibin; Jiang, Fei; Ye, Song; Wu, Yingying; Zhu, Kaiping; Wang, Deping

    2016-05-01

    The strontium-substituted hydroxyapatite microspheres (SrHA) incorporated alginate composite microspheres (SrHA/Alginate) were prepared via adding SrHA/alginate suspension dropwise into calcium chloride solution, in which the gel beads were formed by means of crosslinking reaction. The structure, morphology and in vitro bioactivity of the composite microspheres were studied by using XRD, SEM and EDS methods. The biological behaviors were characterized and analyzed through inductively coupled plasma optical emission spectroscopy (ICP-OES), CCK-8, confocal laser microscope and ALP activity evaluations. The experimental results indicated that the synthetic SrHA/Alginate showed similar morphology to the well-known alginate microspheres (Alginate) and both of them possessed a great in vitro bioactivity. Compared with the control Alginate, the SrHA/Alginate enhanced MC3T3-E1 cell proliferation and ALP activity by releasing osteoinductive and osteogenic Sr ions. Furthermore, vancomycin was used as a model drug to investigate the drug release behaviors of the SrHA/Alginate, Alginate and SrHA. The results suggested that the SrHA/Alginate had a highest drug-loading efficiency and best controlled drug release properties. Additionally, the SrHA/Alginate was demonstrated to be pH-sensitive as well. The increase of the pH value in phosphate buffer solution (PBS) accelerated the vancomycin release. Accordingly, the multifunctional SrHA/Alginate can be applied in the field of bioactive drug carriers and bone filling materials.

  10. Discovery of a Novel Alginate Lyase from Nitratiruptor sp. SB155-2 Thriving at Deep-sea Hydrothermal Vents and Identification of the Residues Responsible for Its Heat Stability.

    PubMed

    Inoue, Akira; Anraku, Moe; Nakagawa, Satoshi; Ojima, Takao

    2016-07-22

    Extremophiles are expected to represent a source of enzymes having unique functional properties. The hypothetical protein NIS_0185, termed NitAly in this study, was identified as an alginate lyase-homolog protein in the genomic database of ϵ-Proteobacteria Nitratiruptor sp. SB155-2, which was isolated from deep-sea hydrothermal vents at a water depth of 1,000 m. Among the characterized alginate lyases in the polysaccharide lyase family 7 (PL-7), the amino acid sequence of NitAly showed the highest identity (39%) with that of red alga Pyropia yezoensis alginate lyase PyAly. Recombinant NitAly (rNitAly) was successfully expressed in Escherichia coli Purified rNitAly degraded alginate in an endolytic manner. Among alginate block types, polyM was preferable to polyG and polyMG as a substrate, and its end degradation products were mainly tri-, tetra-, and penta-saccharides. The optimum temperature and pH values were 70 °C and around 6, respectively. A high concentration of NaCl (0.8-1.4 m) was required for maximum activity. In addition, a 50% loss of activity was observed after incubation at 67 °C for 30 min. Heat stability was decreased in the presence of 5 mm DTT, and Cys-80 and Cys-232 were identified as the residues responsible for heat stability but not lyase activity. Introducing two cysteines into PyAly based on homology modeling using Pseudomonas aeruginosa alginate lyase PA1167 as the template enhanced its heat stability. Thus, NitAly is a functional alginate lyase, with its unique optimum conditions adapted to its environment. These insights into the heat stability of NitAly could be applied to improve that of other PL-7 alginate lyases.

  11. Microencapsulated Aliivibrio fischeri in alginate microspheres for monitoring heavy metal toxicity in environmental waters.

    PubMed

    Futra, Dedi; Heng, Lee Yook; Surif, Salmijah; Ahmad, Asmat; Ling, Tan Ling

    2014-12-05

    In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4-5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples.

  12. Microencapsulated Aliivibrio fischeri in Alginate Microspheres for Monitoring Heavy Metal Toxicity in Environmental Waters

    PubMed Central

    Futra, Dedi; Heng, Lee Yook; Surif, Salmijah; Ahmad, Asmat; Ling, Tan Ling

    2014-01-01

    In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4–5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples. PMID:25490588

  13. In vitro fermentation and prebiotic potential of novel low molecular weight polysaccharides derived from agar and alginate seaweeds.

    PubMed

    Ramnani, Priya; Chitarrari, Roberto; Tuohy, Kieran; Grant, John; Hotchkiss, Sarah; Philp, Kevin; Campbell, Ross; Gill, Chris; Rowland, Ian

    2012-02-01

    Fermentation properties and prebiotic potential of novel low molecular weight polysaccharides (LMWPs) derived from agar and alginate bearing seaweeds was investigated. Ten LMWPs were supplemented to pH, temperature controlled anaerobic batch cultures inoculated with human feces from three donors, in triplicate. Microbiota changes were monitored using Fluorescent in-situ hybridization and short chain fatty acids, the fermentation end products were analysed using gas chromatography. Of the ten LMWPs tested, Gelidium seaweed CC2253 of molecular weight 64.64 KDa showed a significant increase in bifidobacterial populations from log(10) 8.06 at 0 h to log(10) 8.55 at 24 h (p = 0.018). For total bacterial populations, alginate powder CC2238 produced a significant increase from log(10) 9.01 at 0 h to log(10) 9.58 at 24 h (p = 0.032). No changes were observed in the other bacterial groups tested viz. Bacteroides, Lactobacilli/Enterococci, Eubacterium rectale/Clostridium coccoides and Clostridium histolyticum. The polysaccharides also showed significant increases in total SCFA production, particularly acetic and propionic acids, indicating that they were readily fermented. In conclusion, some LMWPs derived from agar and alginate bearing seaweeds were fermented by gut bacteria and exhibited potential to be used a novel source of prebiotics.

  14. Encapsulation of probiotic bacteria with alginate-starch and evaluation of survival in simulated gastrointestinal conditions and in yoghurt.

    PubMed

    Sultana, K; Godward, G; Reynolds, N; Arumugaswamy, R; Peiris, P; Kailasapathy, K

    2000-12-05

    A modified method using calcium alginate for the microencapsulation of probiotic bacteria is reported in this study. Incorporation of Hi-Maize starch (a prebiotic) improved encapsulation of viable bacteria as compared to when the bacteria were encapsulated without the starch. Inclusion of glycerol (a cryo-protectant) with alginate mix increased the survival of bacteria when frozen at -20 degrees C. The acidification kinetics of encapsulated bacteria showed that the rate of acid produced was lower than that of free cultures. The encapsulated bacteria, however, did not demonstrate a significant increase in survival when subjected to in vitro high acid and bile salt conditions. A preliminary study was carried out in order to monitor the effects of encapsulation on the survival of Lactobacillus acidophilus and Bifidobacterium spp. in yoghurt over a period of 8 weeks. This study showed that the survival of encapsulated cultures of L. acidophilus and Bifidobacterium spp. showed a decline in viable count of about 0.5 log over a period of 8 weeks while there was a decline of about 1 log in cultures which were incorporated as free cells in yoghurt. The encapsulation method used in this study did not result in uniform bead size, and hence additional experiments need to be designed using uniform bead size in order to assess the role of different encapsulation parameters, such as bead size and alginate concentration, in providing protection to the bacteria.

  15. Oyster mushroom’s lipase enzyme entrapment on calcium alginate as biocatalyst in the synthesis of lauryl diethanolamide

    NASA Astrophysics Data System (ADS)

    Wijayati, N.; Masubah, K.; Supartono

    2017-02-01

    Lipase is an enzyme with large biotechnology applications, such as hydrolysis in the food industry, applications in chemical industry, synthesis of polymers and surfactants. Lipase was isolated from oyster mushroom with activity 0,93 U/mg and protein content 1,1234 mg/mL. Lipase was immobilized by entrapment method in a matrix of Ca-alginate. This report describes that we have developed for the synthesis of lauryl diethanolamide The result showed that the optimum condition of lipase immobilization was achieved on 3% Na-alginate solution with protein content 0,84 mg/mL and the activity 3,33 U/mg. An amide (22.911%) formed from the amidation of lauric acid and diethanolamine.

  16. Extraction and physicochemical characterization of Sargassum vulgare alginate from Brazil.

    PubMed

    Torres, Marcia R; Sousa, Alessandra P A; Silva Filho, Eduardo A T; Melo, Dirce F; Feitosa, Judith P A; de Paula, Regina C M; Lima, Maria G S

    2007-10-15

    Alginate fractions from Sargassum vulgare brown seaweed were characterized by (1)H NMR and fluorescence spectroscopy and by rheological measurements. The alginate extraction conditions were investigated. In order to carry out the structural and physicochemical characterization, samples extracted for 1 and 5h at 60 degrees C were further purified by re-precipitation with ethanol and denoted as SVLV (S. vulgare low viscosity) and SVHV (S. vulgare high viscosity), respectively. The M/G ratio values for SVLV and SVHV were 1.56 and 1.27, respectively, higher than the ratio for most Sargassum spp. alginates (0.19-0.82). The homopolymeric blocks F(GG) and F(MM) of these fractions characterized by (1)H NMR spectroscopy were 0.43 and 0.55 for SVHV and 0.36 and 0.58 for SVLV samples, respectively, these values typically being within 0.28-0.77 and 0.07-0.41, respectively. Therefore, the alginate samples from S. vulgare are much richer in mannuronic block structures than those from other Sargassum species. Values of M(w) for alginate samples were also calculated using intrinsic viscosity data. The M(w) value for SVLV (1.94 x 10(5)g/mol) was lower than that for SVHV (3.3 x 10(5)g/mol). Newtonian behavior was observed for a solution concentration as high as 0.7% for SVLV, while for SVHV the solutions behaved as a Newtonian fluid up to 0.5%. The optimal conditions for obtaining the alginates from S. vulgare were 60 degrees C and 5h extraction. Under these conditions, a more viscous alginate in higher yield was extracted from the seaweed biomass.

  17. Controlled release of Lactobacillus rhamnosus biofilm probiotics from alginate-locust bean gum microcapsules.

    PubMed

    Cheow, Wean Sin; Kiew, Tie Yi; Hadinoto, Kunn

    2014-03-15

    Chitosan-coated alginate microcapsules containing high-density biofilm Lactobacillus rhamnosus have been previously shown to exhibit higher freeze drying- and thermal-tolerance than their planktonic counterparts. However, their cell release profile remains poor due to the capsules' susceptibility to the gastric environment. Herein the effects of adding locust bean (LB) and xanthan (XT) gums to alginate (AGN) capsules on the stress tolerance and cell release profiles in simulated gastrointestinal fluids are investigated. Compared to the AGN-only capsules, the AGN-LB capsules exhibit improved stress tolerance (i.e. ≈ 6x for freeze drying, 100x for thermotolerance, 10x for acid), whereas the AGN-XT capsules only improve the acid tolerance. Importantly, the AGN-LB capsules possess the optimal cell release profile with a majority of cells released in the simulated intestinal juice than in the gastric juice. The AGN-LB capsules' superiority is attributed to their stronger interaction with the chitosan coating and high swelling capacity, thus delaying their bulk dissolution.

  18. Is there a cause-and-effect relationship between physicochemical properties and cell behavior of alginate-based hydrogel obtained after sterilization?

    PubMed

    Yu, Hao; Cauchois, Ghislaine; Schmitt, Jean-François; Louvet, Nicolas; Six, Jean-Luc; Chen, Yun; Rahouadj, Rachid; Huselstein, Céline

    2017-01-25

    Alginate-based hydrogel scaffolds are widely used in the field of cartilage regeneration and repair. If the effect of autoclaving on the alginate powder is well known, it is not the same for the possible effects of the sterilization UV treatment on the properties of the hydrogel after polymerization. To select an effective sterilization treatment of alginate-based materials, one must find what are inter-relationship between the characteristics (chemical, physical and mechanical) of alginate-based hydrogel during sterilization, and what consequences have affected on cell behavior. In this study, we investigated the influence of UV sterilization treatments (UV-1 and UV-2: 25 and 50min, respectively) and autoclaving to obtain alginate (Alg)/hyaluronic acid (HA) hydrogel, as well as further evaluated the relationship between physicochemical properties and cell behavior of Alg/HA hydrogel after UVs and autoclaving. The physicochemical properties of this mixture at the powder or polymerized states were analyzed using ATR-FTIR, HPLC-SEC, rheological, indentation testing and sterility testing. The cell behaviors of hydrogels were evaluated by cell viability and proliferation, and chondrogenic differentiation. The effects of treatment parameters and their correlation with the others characteristics were determined statistically by Principal Component Analysis (PCA). In this study, we have shown that the cell behavior in alginate-based hydrogels was not only regulated by physicochemical properties (as molar mass or/and viscosity), but also associated with the controlling of sterilization time. It can provide a basis for choosing an effective method of sterilization, which can keep the mechanical or physical-chemical properties of Alg-based hydrogel scaffold and maintain its cytocompatibility and its ability to induce chondrogenesis from mesenchymal stem cells.

  19. Long-term function of islets encapsulated in a re-designed alginate microcapsule construct in omentum pouches of immune-competent diabetic rats

    PubMed Central

    Pareta, Rajesh; McQuilling, John P; Sittadjody, Sivanandane; Jenkins, Randy; Bowden, Stephen; Orlando, Giuseppe; Farney, Alan C; Brey, Eric M; Opara, Emmanuel C

    2014-01-01

    Objectives Our study aim was to determine encapsulated islet graft viability in an omentum pouch and the effect of FGF-1 released from our redesigned alginate microcapsules on the function of the graft. Methods Isolated rat islets were encapsulated in an inner core made with 1.5% low-viscosity high-mannuronic acid (LVM) alginate followed by an external layer made with 1.25% low-viscosity high-guluronic acid (LVG) alginate with or without FGF-1, in microcapsules measuring 300 – 400 μm in diameter. The two alginate layers were separated by a perm-selective membrane made with 0.1 % Poly-L-Ornithine (PLO), and the inner LVM core was partially chelated using 55 mM sodium citrate for 2 min. Results A marginal mass of encapsulated islet allografts (~2000 islets/kg) in Streptozotocin-diabetic Lewis rats caused significant reduction in blood glucose levels similar to the effect observed with encapsulated islet isografts. Transplantation of allo-islets co-encapsulated with FGF-1 did not result in better glycemic control, but induced greater body weight maintenance in transplant recipients compared to those that received only allo-islets. Histological examination of the retrieved tissue demonstrated morphologically and functionally intact islets in the microcapsules, with no signs of fibrosis. Conclusion We conclude that the omentum is a viable site for encapsulated islet transplantation. PMID:24681880

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

    PubMed

    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.

  1. Oxidized alginate hydrogels as niche environments for corneal epithelial cells.

    PubMed

    Wright, Bernice; De Bank, Paul A; Luetchford, Kim A; Acosta, Fernando R; Connon, Che J

    2014-10-01

    Chemical and biochemical modification of hydrogels is one strategy to create physiological constructs that maintain cell function. The aim of this study was to apply oxidised alginate hydrogels as a basis for development of a biomimetic niche for limbal epithelial stem cells that may be applied to treating corneal dysfunction. The stem phenotype of bovine limbal epithelial cells (LEC) and the viability of corneal epithelial cells (CEC) were examined in oxidised alginate gels containing collagen IV over a 3-day culture period. Oxidation increased cell viability (P ≤ 0.05) and this improved further with addition of collagen IV (P ≤ 0.01). Oxidised gels presented larger internal pores (diameter: 0.2-0.8 µm) than unmodified gels (pore diameter: 0.05-0.1 µm) and were significantly less stiff (P ≤ 0.001), indicating that an increase in pore size and a decrease in stiffness contributed to improved cell viability. The diffusion of collagen IV from oxidised alginate gels was similar to that of unmodified gels suggesting that oxidation may not affect the retention of extracellular matrix proteins in alginate gels. These data demonstrate that oxidised alginate gels containing corneal extracellular matrix proteins can influence corneal epithelial cell function in a manner that may impact beneficially on corneal wound healing therapy.

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

    PubMed Central

    Sarei, F.; Dounighi, N. Mohammadpour; Zolfagharian, H.; Khaki, P.; Bidhendi, S. Moradi

    2013-01-01

    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. PMID:24302799

  3. Zinc cross-linked hydroxamated alginates for pulsed drug release

    PubMed Central

    Raut, Neha S; Deshmukh, Prasad R; Umekar, Milind J; Kotagale, Nandkishor R

    2013-01-01

    Introduction: Alginates can be tailored chemically to improve solubility, physicochemical, and biological properties and its complexation with metal ion is useful for controlling the drug release. Materials And Methods: Synthesized N,O-dimethyl, N-methyl, or N-Benzyl hydroxylamine derivatives of sodium alginate were subsequently complexed with zinc to form beads. Hydroxamation of sodium alginate was confirmed by Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC). Results: The synthesized polymeric material exhibited reduced aqueous, HCl and NaOH solubility. The hydroxamated derivatives demonstrated pulsed release where change in pH of the dissolution medium stimulated the atenolol release. Conclusion: Atenolol loaded Zn cross-linked polymeric beads demonstrated the sustained the plasma drug levels with increased half-life. Although the synthesized derivatives greatly altered the aqueous solubility of sodium alginate, no significant differences in in vitro and in vivo atenolol release behavior amongst the N,O-dimethyl, N-methyl, or N-Benzyl hydroxylamine derivatives of sodium alginate were observed. PMID:24350039

  4. Encapsulation optimization of lemon balm antioxidants in calcium alginate hydrogels.

    PubMed

    Najafi-Soulari, Samira; Shekarchizadeh, Hajar; Kadivar, Mahdi

    2016-11-01

    Calcium alginate hydrogel beads were used to encapsulate lemon balm extract. Chitosan layer was used to investigate the effect of hydrogel coating. To determine the interactions of antioxidant compounds of extract with encapsulation materials and its stability, microstructure of hydrogel beads was thoroughly monitored using scanning electron microscopy and Fourier transform infrared (FTIR). Total polyphenols content and antiradical activity of lemon balm extract were also evaluated before and after encapsulation. Three significant parameters (lemon balm extract, sodium alginate, and calcium chloride concentrations) were optimized by response surface methodology to obtain maximum encapsulation efficiency. The FTIR spectra showed no interactions between extract and polymers as there were no new band in spectra of alginate hydrogel after encapsulation of active compounds of lemon balm extract. The antioxidant activity of lemon balm extract did not change after encapsulation. Therefore, it was found that alginate is a suitable material for encapsulation of natural antioxidants. Sodium alginate solution concentration, 1.84%, lemon balm extract concentration, 0.4%, and calcium chloride concentration, 0.2% was determined to be the optimum condition to reach maximum encapsulation efficiency.

  5. Oxidized alginate hydrogels as niche environments for corneal epithelial cells

    PubMed Central

    Wright, Bernice; De Bank, Paul A; Luetchford, Kim A; Acosta, Fernando R; Connon, Che J

    2014-01-01

    Chemical and biochemical modification of hydrogels is one strategy to create physiological constructs that maintain cell function. The aim of this study was to apply oxidised alginate hydrogels as a basis for development of a biomimetic niche for limbal epithelial stem cells that may be applied to treating corneal dysfunction. The stem phenotype of bovine limbal epithelial cells (LEC) and the viability of corneal epithelial cells (CEC) were examined in oxidised alginate gels containing collagen IV over a 3-day culture period. Oxidation increased cell viability (P ≤ 0.05) and this improved further with addition of collagen IV (P ≤ 0.01). Oxidised gels presented larger internal pores (diameter: 0.2–0.8 µm) than unmodified gels (pore diameter: 0.05–0.1 µm) and were significantly less stiff (P ≤ 0.001), indicating that an increase in pore size and a decrease in stiffness contributed to improved cell viability. The diffusion of collagen IV from oxidised alginate gels was similar to that of unmodified gels suggesting that oxidation may not affect the retention of extracellular matrix proteins in alginate gels. These data demonstrate that oxidised alginate gels containing corneal extracellular matrix proteins can influence corneal epithelial cell function in a manner that may impact beneficially on corneal wound healing therapy. © 2013 The Authors. Journal of Biomedical Materials Research Part A Published byWiley Periodicals, Inc. Part A: 102A: 3393–3400, 2014. PMID:24142706

  6. AAS Career Services

    NASA Astrophysics Data System (ADS)

    Marvel, Kevin B.

    2012-08-01

    The American Astronomical Society provides substantial programs in the area of Career Services.Motivated by the Society's mission to enhance and share humanity's understanding of the Universe, the AAS provides a central resource for advertising positions, interviewing opportunities at its annual winter meeting and information, workshops and networks to enable astronomers to find employment.The programs of the Society in this area are overseen by an active committee on employment and the AAS Council itself.Additional resources that help characterize the field, its growth and facts about employment such as salaries and type of jobs available are regularly summarized and reported on by the American Institute of Physics.

  7. P. aeruginosa SGNH Hydrolase-Like Proteins AlgJ and AlgX Have Similar Topology but Separate and Distinct Roles in Alginate Acetylation

    PubMed Central

    Moynihan, Patrick J.; Kitova, Elena N.; Walvoort, Marthe T. C.; Little, Dustin J.; Whitney, John C.; Dawson, Karen; Weadge, Joel T.; Robinson, Howard; Ohman, Dennis E.; Codée, Jeroen D. C.; Klassen, John S.; Clarke, Anthony J.; Howell, P. Lynne

    2014-01-01

    The O-acetylation of polysaccharides is a common modification used by pathogenic organisms to protect against external forces. Pseudomonas aeruginosa secretes the anionic, O-acetylated exopolysaccharide alginate during chronic infection in the lungs of cystic fibrosis patients to form the major constituent of a protective biofilm matrix. Four proteins have been implicated in the O-acetylation of alginate, AlgIJF and AlgX. To probe the biological function of AlgJ, we determined its structure to 1.83 Å resolution. AlgJ is a SGNH hydrolase-like protein, which while structurally similar to the N-terminal domain of AlgX exhibits a distinctly different electrostatic surface potential. Consistent with other SGNH hydrolases, we identified a conserved catalytic triad composed of D190, H192 and S288 and demonstrated that AlgJ exhibits acetylesterase activity in vitro. Residues in the AlgJ signature motifs were found to form an extensive network of interactions that are critical for O-acetylation of alginate in vivo. Using two different electrospray ionization mass spectrometry (ESI-MS) assays we compared the abilities of AlgJ and AlgX to bind and acetylate alginate. Binding studies using defined length polymannuronic acid revealed that AlgJ exhibits either weak or no detectable polymer binding while AlgX binds polymannuronic acid specifically in a length-dependent manner. Additionally, AlgX was capable of utilizing the surrogate acetyl-donor 4-nitrophenyl acetate to catalyze the O-acetylation of polymannuronic acid. Our results, combined with previously published in vivo data, suggest that the annotated O-acetyltransferases AlgJ and AlgX have separate and distinct roles in O-acetylation. Our refined model for alginate acetylation places AlgX as the terminal acetlytransferase and provides a rationale for the variability in the number of proteins required for polysaccharide O-acetylation. PMID:25165982

  8. Modifying the OPLS-AA force field to improve hydration free energies for several amino acid side chains using new atomic charges and an off-plane charge model for aromatic residues.

    PubMed

    Xu, Zhitao; Luo, Harry H; Tieleman, D Peter

    2007-02-01

    The hydration free energies of amino acid side chains are an important determinant of processes that involve partitioning between different environments, including protein folding, protein complex formation, and protein-membrane interactions. Several recent papers have shown that calculated hydration free energies for polar and aromatic residues (Trp, His, Tyr, Asn, Gln, Asp, Glu) in several common molecular dynamics force fields differ significantly from experimentally measured values. We have attempted to improve the hydration energies for these residues by modifying the partial charges of the OPLS-AA force field based on natural population analysis of density functional theory calculations. The resulting differences between calculated hydration free energies and experimental results for the seven side chain analogs are less than 0.1 kcal/mol. Simulations of the synthetic Trp-rich peptide Trpzip2 show that the new charges lead to significantly improved geometries for interacting Trp-side chains. We also investigated an off-plane charge model for aromatic rings that more closely mimics their electronic configuration. This model results in an improved free energy of hydration for Trp and a somewhat altered benzene-sodium potential of mean force with a more favorable energy for direct benzene-sodium contact.

  9. Influence of both cation and alginate nature on the rheological behavior of transition metal alginate gels.

    PubMed

    Agulhon, Pierre; Robitzer, Mike; Habas, Jean-Pierre; Quignard, Françoise

    2014-11-04

    The rheological properties of several ionotropic alginate hydrogels were investigated according to the nature of the divalent cation (Mn(2+), Co(2+), Cu(2+)) and the guluronic fraction of the alginate (HG and LG for "high G-content" and "low G-content"). Six hydrogels (Mn-LG, Mn-HG, Co-LG, Co-HG, Cu-LG and Cu-HG) were synthesized and studied by spectromechanical analyses. On one hand, Cu-HG, Cu-LG and Co-HG behaved as viscoelastic solids: the elastic contribution was higher than the dissipative component in all the frequency range studied (G'>G"). No flow zone (G">G') was detected even at very low values of the shearing frequency. On the other, Mn-HG, Mn-LG and Co-LG presented a spectromechanical behavior that resembled that observed classically for entangled polymers. Indeed, at high frequency, these latter materials could be compared to a viscoelastic solid but at low frequency, the flow zone was described and the viscous character became prevalent with finite relaxation time. Very good correlations with the microscopic structurations of the network were evidenced (rubbery vs. flow zone and fibrillar vs. complex morphology respectively).

  10. Regulation of uterine and umbilical amino acid uptakes by maternal amino acid concentrations.

    PubMed

    Thureen, P J; Anderson, S M; Hay, W W

    2000-09-01

    We tested the hypothesis that decreased fetal amino acid (AA) supply, produced by maternal hypoaminoacidemia (low AA) during hyperglycemia (HG), is reversible with maternal AA infusion and regulates fetal insulin concentration ([I]). We measured net uterine and umbilical AA uptakes during maternal HG/low AA concentration ([AA]) and after maternal intravenous infusion of a mixed AA solution. After 5 days HG, all maternal [AA] except glycine were decreased >50%, particularly essential [AA] (P < 0.00005). Most fetal [AA] also were decreased, especially branched-chain AA (P < 0.001). Maternal AA infusion increased net uterine uptakes of Val, Leu, Ile, Met, and Ser and net umbilical uptakes of Val, Leu, Ile, Met, Phe, and Arg but did not change net uteroplacental uptake of any AA. Fetal [I] increased 55 +/- 14%, P < 0.001, with correction of fetal [AA], despite the lack of change in fetal glucose concentration. Thus generalized maternal hypoaminoacidemia decreases uterine and umbilical uptakes of primarily the essential AA and decreases fetal branched-chain [AA]. These changes are reversed with correction of maternal [AA], which also increases fetal [I].

  11. Impact of alginate-producing Pseudomonas aeruginosa on alveolar macrophage apoptotic cell clearance.

    PubMed

    McCaslin, Charles A; Petrusca, Daniela N; Poirier, Christophe; Serban, Karina A; Anderson, Gregory G; Petrache, Irina

    2015-01-01

    Pseudomonas aeruginosa infection is a hallmark of lung disease in cystic fibrosis. Acute infection with P. aeruginosa profoundly inhibits alveolar macrophage clearance of apoptotic cells (efferocytosis) via direct effect of virulence factors. During chronic infection, P. aeruginosa evades host defense by decreased virulence, which includes the production or, in the case of mucoidy, overproduction of alginate. The impact of alginate on innate immunity, in particular on macrophage clearance of apoptotic cells is not known. We hypothesized that P. aeruginosa strains that exhibit reduced virulence impair macrophage clearance of apoptotic cells and we investigated if the polysaccharide alginate produced by mucoid P. aeruginosa is sufficient to inhibit alveolar macrophage efferocytosis. Rat alveolar or human peripheral blood monocyte (THP-1)-derived macrophage cell lines were exposed in vitro to exogenous alginate or to wild type or alginate-overproducing mucoid P. aeruginosa prior to challenge with apoptotic human Jurkat T-lymphocytes. The importance of LPS contamination and that of structural integrity of alginate polymers was tested using alginate of different purities and alginate lyase, respectively. Alginate inhibited alveolar macrophage efferocytosis in a dose- and time-dependent manner. This effect was augmented but not exclusively attributed to lipopolysaccharide (LPS) present in alginates. Alginate-producing P. aeruginosa inhibited macrophage efferocytosis by more than 50%. A mannuronic-specific alginate lyase did not restore efferocytosis inhibited by exogenous guluronic-rich marine alginate, but had a marked beneficial effect on efferocytosis of alveolar macrophages exposed to mucoid P. aeruginosa. Despite decreased virulence, mucoid P. aeruginosa may contribute to chronic airway inflammation through significant inhibition of alveolar clearance of apoptotic cells and debris. The mechanism by which mucoid bacteria inhibit efferocytosis may involve alginate

  12. cDNA cloning and bacterial expression of a PL-14 alginate lyase from a herbivorous marine snail Littorina brevicula.

    PubMed

    Rahman, Mohammad Matiur; Wang, Ling; Inoue, Akira; Ojima, Takao

    2012-10-01

    Herbivorous marine snails like Littorina species are known to possess alginate lyases in their digestive tracts. The Littorina enzymes have been identified as endolytic polymannuronate (poly(M)) lyases (EC 4.2.2.3); however, it is still unclear which polysaccharide-lyase family (PL) the Littorina enzymes belong to, since no complete primary structure of Littorina enzymes has been determined. Thus, in the present study, we analyzed the primary structure of LbAly28, a 28kDa alginate lyase isozyme of Littorina brevicula, by the cDNA method. LbAly28 cDNAs were amplified by PCR followed by 5'- and 3'-RACE PCRs from the L. brevicula hepatopancreas cDNA. A cDNA covering entire coding region of LbAly28 consisted of 1129bp and encoded an amino-acid sequence of 291 residues. The deduced amino-acid sequence comprised an initiation methionine, a putative signal peptide of 14 residues, a propeptide-like region of 16 residues, and a mature LbAly28 domain of 260 residues. The mature LbAly28 domain showed 43-53% amino-acid identities with other molluscan PL-14 enzymes. The catalytically important residues in PL-14 enzymes, which were identified in the Chlorella virus glucuronate-specific lyase vAL-1 and Aplysia poly(M) lyase AkAly30, were also conserved in LbAly28. Site-directed mutagenesis regarding these residues, that is, replacements of Lys94, Lys97, Thr121, Arg 123, Tyr135, and Tyr137 to Ala, decreased the activity of recombinant LbAly28 to various degrees. From these results we concluded that LbAly28 is a member of PL-14 alginate lyases. Besides the effects of above mutations, we noticed that the replacement of T121 by Ala changed the substrate preference of LbAly28. Namely, the activities toward sodium alginate and poly(MG)-block substrate increased and became comparable with the activity toward poly(M)-block substrate. This suggests that the region including T121 of LbAly28 closely relates to the recognition of poly(MG) region of alginate.

  13. Methylene blue adsorption on graphene oxide/calcium alginate composites.

    PubMed

    Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Wang, Yonghao; Wu, Shaoling; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

    2013-06-05

    Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81 mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature.

  14. Fundamental Characteristics of Bioprint on Calcium Alginate Gel

    NASA Astrophysics Data System (ADS)

    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.

  15. Alginate based polyurethanes: A review of recent advances and perspective.

    PubMed

    Zia, Khalid Mahmood; Zia, Fatima; Zuber, Mohammad; Rehman, Saima; Ahmad, Mirza Nadeem

    2015-08-01

    The trend of using biopolymers in combination with synthetic polymers was increasing rapidly from last two or three decades. Polysaccharide based biopolymers especially starch, cellulose, chitin, chitosan, alginate, etc. found extensive applications for different industrial uses, as they are biocompatible, biodegradable, bio-renewable resources and chiefly environment friendly. Segment block copolymer character of polyurethanes that endows them a broad range of versatility in terms of tailoring their properties was employed in conjunction with various natural polymers resulted in modified biomaterials. Alginate is biodegradable, biocompatible, bioactive, less toxic and low cost anionic polysaccharide, as a part of structural component of bacteria and brown algae (sea weed) is quite abundant in nature. It is used in combination with polyurethanes to form elastomers, nano-composites, hydrogels, etc. that especially revolutionized the food and biomedical industries. The review summarized the development in alginate based polyurethanes with their potential applications.

  16. Postelectrospinning modifications for alginate nanofiber-based wound dressings.

    PubMed

    Leung, Victor; Hartwell, Ryan; Elizei, Sanam Salimi; Yang, Heejae; Ghahary, Aziz; Ko, Frank

    2014-04-01

    Alginate nanofibers have been attractive for potential tissue regeneration applications due to a combination of their moisture retention ability and large surface area available in a nonwoven nanofiber form. This study aims to address several challenges in alginate nanofiber application, including the lack of structural stability in aqueous environment and limited cell attachment as compared to commercial wound dressings, via examining crosslinking techniques. In addition to the commonly performed divalent ion crosslinking, a glutaraldehyde double-crosslinking step and polylysine addition were applied to an electrospun alginate nanofiber nonwoven mat. With optimization of the electrospinning solution, nanofiber morphology was maintained after the two-stage crosslinking process. Extensibility of the nanofiber mat reduced after the crosslinking process. However, both aqueous stability and cell attachment improved after the postspinning modifications, as shown through degradation tests in phosphate buffered saline solutions and fibroblast cell culture studies, respectively.

  17. Chitosan-alginate nanocapsules for encapsulation of turmeric oil.

    PubMed

    Lertsutthiwong, P; Rojsitthisak, P

    2011-12-01

    Turmeric oil is widely used in pharmaceutical and cosmetic applications because of its antibacterial, antifungal, antioxidant, and insect-repellent properties. However, turmeric oil is volatile, insoluble in water and unstable in certain environments, which causes difficulties with formulation development and stability of new products. One approach to overcome these problems is to encapsulate turmeric oil in carriers formed from naturally occurring polysaccharides. Among such polysaccharides, chitosan and alginate have been widely used as particulate carriers for encapsulation and controlled release of bioactive compounds. The potential for size reduction of the carriers to the nanometer scale is of particular interest for delivery systems. In this review, we provide an overview of the versatile properties of turmeric oil and discuss the use of alginate and chitosan for capsule formation and encapsulation of turmeric oil in chitosan-alginate nanocapsules. We also discuss the in vitro skin permeation of turmeric oil from nanocapsules.

  18. Removable colored coatings based on calcium alginate hydrogels.

    PubMed

    Kobaslija, Muris; McQuade, D Tyler

    2006-08-01

    This article describes the creation of a nontoxic, biodegradable coating using calcium alginate and FD&C approved dyes. The coating is robust but is rapidly removed upon treatment with disodium ethylenediamine tetraacetate (EDTA). Dye leaching from calcium alginate films was studied, and it was determined that the efficiency of dye retention is proportional to the degree of cross-linking. Degradation rates were studied on calcium alginate beads serving as a model for a coating. We determined that degradation rates depend on the gel's cross-linking and on the amount of EDTA used. Bead size also influenced the degradation rates; smaller beads degraded faster than larger beads. We show that the coating can be used as an easily removable and environmentally friendly logotype on an artificial turf surface. Applications of these coatings can be extended to food, cosmetic, medicinal, and textile uses and to wherever nontoxic, easily removable colored coating is desired.

  19. Alginate Overproduction Affects Pseudomonas aeruginosa Biofilm Structure and Function

    PubMed Central

    Hentzer, Morten; Teitzel, Gail M.; Balzer, Grant J.; Heydorn, Arne; Molin, Søren; Givskov, Michael; Parsek, Matthew R.

    2001-01-01

    During the course of chronic cystic fibrosis (CF) infections, Pseudomonas aeruginosa undergoes a conversion to a mucoid phenotype, which is characterized by overproduction of the exopolysaccharide alginate. Chronic P. aeruginosa infections involve surface-attached, highly antibiotic-resistant communities of microorganisms organized in biofilms. Although biofilm formation and the conversion to mucoidy are both important aspects of CF pathogenesis, the relationship between them is at the present unclear. In this study, we report that the overproduction of alginate affects biofilm development on an abiotic surface. Biofilms formed by an alginate-overproducing strain exhibit a highly structured architecture and are significantly more resistant to the antibiotic tobramycin than a biofilm formed by an isogenic nonmucoid strain. These results suggest that an important consequence of the conversion to mucoidy is an altered biofilm architecture that shows increasing resistance to antimicrobial treatments. PMID:11514525

  20. AAS Oral History Project

    NASA Astrophysics Data System (ADS)

    Buxner, Sanlyn; Holbrook, Jarita; AAS Oral History Team

    2016-06-01

    Now in its fourth year, the AAS Oral History Project has interviewed over 80 astronomers from all over the world. Led by the AAS Historical Astronomy Division (HAD) and partially funded by the American Institute of Physics Niels Bohr Library and ongoing support from the AAS, volunteers have collected oral histories from astronomers at professional meetings starting in 2015, including AAS, DPS, and the IAU general assembly. Each interview lasts one and a half to two hours and focuses on interviewees’ personal and professional lives. Questions include those about one’s family, childhood, strong influences on one’s scientific career, career path, successes and challenges, perspectives on how astronomy is changing as a field, and advice to the next generation. Each interview is audio recorded and transcribed, the content of which is checked with each interviewee. Once complete, interview transcripts are posted online as part of a larger oral history library at https://www.aip.org/history-programs/niels-bohr-library/oral-histories. Future analysis will reveal a rich story of astronomers and will help the community address issues of diversity, controversies, and the changing landscape of science. We are still recruiting individuals to be interviewed from all stages of career from undergraduate students to retired and emeritus astronomers. Contact Jarita Holbrook to schedule an interview or to find out more information about the project (astroholbrook@gmail.com). Also, contact Jarita Holbrook if you would like to become an interviewer for the project.

  1. Core-corona PSt/P(BA-AA) composite particles by two-stage emulsion polymerization

    NASA Astrophysics Data System (ADS)

    Xie, Delong; Ren, Xiaolin; Zhang, Xinya; Liao, Shijun

    2016-03-01

    Raspberry-shaped composite particles with polystyrene (PSt) as core and poly(n-butyl acrylate-co-acrylic acid) (P(BA-AA)) as corona were synthesized via emulsion polymerization. The random copolymer, P(BA-AA), was pre-prepared and used as a polymeric surfactant, its emulsifying properties adjusted by changing the mass ratio of BA and AA. The morphology of the resulting core-corona composite particles, P(St/P(BA-AA)), could be regulated and controlled by varying the concentrations of P(BA-AA) or the mass ratio of BA:AA in P(BA-AA). The experimental results indicate that 3.0-6.0 wt% of P(BA-AA) is required to obtain stable composite emulsions, and P(BA-AA) with a mass ratio of BA:AA = 1:2 is able to generate distinct core-corona structures. A mechanism of composite particle formation is proposed based on the high affinity between the PSt core and the hydrophobic segments of P(BA-A). The regular morphology of the colloidal film is expected to facilitate potential application of core-corona particles in the field of light scattering. Furthermore, the diversity of core-corona particles can be expanded by replacing P(BA-AA) corona particles with other amphiphilic particles.

  2. Effect of Sodium Alginate on Staphylococcus aureus During Mild Heating and Freezing1

    PubMed Central

    Scott, Lelia G.; Strong, Dorothy H.

    1964-01-01

    The effects of sodium alginate on Staphyiococcus aureus 196 exposed to mild heating or to freezing at -21 C were studied. The addition of sodium alginate to a diluent appeared to confer some protection of viable cells during mild heating. The effect of the presence of sodium alginate in the suspending media during freezing was less clear. There was a slight trend, not statistically significant, for greater reduction in numbers of viable cells at the low temperature when 4% alginate was present in phosphate buffer. Results indicated that the value of sodium alginate in controlling this food-poisoning microorganism in frozen food is questionable. PMID:14131363

  3. A microfluidic approach to encapsulate living cells in uniform alginate hydrogel microparticles.

    PubMed

    Martinez, Carlos J; Kim, Jin Woong; Ye, Congwang; Ortiz, Idelise; Rowat, Amy C; Marquez, Manuel; Weitz, David

    2012-07-01

    A microfluidic technique is described to encapsulate living cells in alginate hydrogel microparticles generated from monodisperse double-emulsion templates. A microcapillary device is used to fabricate double emulsion templates composed of an alginate drop surrounded by a mineral oil shell. Hydrogel formation begins when the alginate drop separates from the mineral oil shell and comes into contact with Ca(2+) ions in the continuous phase. Alginate hydrogel microparticles with diameters ranging from 60 to 230 µm are obtained. 65% of the cells encapsulated in the alginate microparticles were viable after one week. The technique provides a useful means to encapsulate the living cells in monodisperse hydrogel microparticles.

  4. Rheological properties of aqueous Pluronic-alginate systems containing liposomes.

    PubMed

    Grassi, G; Crevatin, A; Farra, R; Guarnieri, G; Pascotto, A; Rehimers, B; Lapasin, R; Grassi, M

    2006-09-01

    Rheological and erosion studies regarding a liposome-containing polymeric blend that is propaedeutic to its use in paving techniques in tubular organs, such as blood vessels, are reported. Attention is focused on an aqueous polymeric blend composed of Pluronic (PF127) and alginate (Protanal LF 10/60) because both polymers, when dissolved in water at a sufficiently high concentration, are subjected to different structural mechanisms, which are driven by temperature increase and addition of bivalent cations, respectively, and both result in marked viscoelastic and plastic properties. After proving the compatibility between PF127 and alginate, we show that the structural transition temperature of the blend, T(ST), can be properly modulated. In particular, we found that T(ST) for an aqueous solution of pure Pluronic 20% w/w is about 21 degrees C and that even slight reductions in polymer concentration result in considerable T(ST) decrease. The addition of salts or alginate (provided as Na-alginate) provokes a substantial decrease of T(ST) and thus the alginate concentration in the blend should not exceed 1% w/w. In addition, liposomes slow down the structural transition but do not substantially affect the rheological properties of the system in the final state at higher temperatures, thus showing that they can be added to the polymeric blend without significant effects. Finally, erosion tests show that after contact with a source of bivalent cations, the polymeric blend containing PF127 and alginate shows an erosion resistance neatly improved with respect to the simple structured Pluronic system having the same polymer concentration. As a whole, all these results constitute the basis for future potential applications of the considered polymeric blend in tubular organs such as blood vessels.

  5. Sustained release of a water-soluble drug from alginate matrix tablets prepared by wet granulation method.

    PubMed

    Mandal, Sanchita; Basu, Sanat Kumar; Sa, Biswanath

    2009-01-01

    Alginate matrix tablet of diltiazem hydrochloride (DTZ), a water-soluble drug, was prepared using sodium alginate (SAL) and calcium gluconate (CG) by the conventional wet granulation method for sustained release of the drug. The effect of formulation variables like SAL/CG ratio, drug load, microenvironmental pH modulator, and processing variable like compression force on the extent of drug release was examined. The tablets prepared with 1:2 w/w ratio of SAL/CG produced the most sustained release of the drug extending up to 13.5 h. Above and below this ratio, the drug release was faster. The drug load and the hardness of the tablets produced minimal variation in drug release. The addition of alkaline or acidic microenvironmental modulators did not extend the release; instead, these excipients produced somewhat faster release of diltiazem. This study revealed that proper selection of SAL/CG ratio is important to produce alginate matrix tablet by wet granulation method for sustained release of DTZ.

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

    PubMed

    Schmitt, Andreas; Rödel, Philipp; Anamur, Cihad; Seeliger, Claudine; Imhoff, Andreas B; Herbst, Elmar; Vogt, Stephan; van Griensven, Martijn; Winter, Gerhard; Engert, Julia

    2015-01-01

    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.

  7. Calcium Alginate Gels as Stem Cell Matrix – Making Paracrine Stem Cell Activity Available for Enhanced Healing after Surgery

    PubMed Central

    Schmitt, Andreas; Rödel, Philipp; Anamur, Cihad; Seeliger, Claudine; Imhoff, Andreas B.; Herbst, Elmar; Vogt, Stephan; van Griensven, Martijn; Winter, Gerhard; Engert, Julia

    2015-01-01

    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. PMID:25793885

  8. 3D Porous Calcium-Alginate Scaffolds Cell Culture System Improved Human Osteoblast Cell Clusters for Cell Therapy

    PubMed Central

    Chen, Ching-Yun; Ke, Cherng-Jyh; Yen, Ko-Chung; Hsieh, Hui-Chen; Sun, Jui-Sheng; Lin, Feng-Huei

    2015-01-01

    Age-related orthopedic disorders and bone defects have become a critical public health issue, and cell-based therapy is potentially a novel solution for issues surrounding bone tissue engineering and regenerative medicine. Long-term cultures of primary bone cells exhibit phenotypic and functional degeneration; therefore, culturing cells or tissues suitable for clinical use remain a challenge. A platform consisting of human osteoblasts (hOBs), calcium-alginate (Ca-Alginate) scaffolds, and a self-made bioreactor system was established for autologous transplantation of human osteoblast cell clusters. The Ca-Alginate scaffold facilitated the growth and differentiation of human bone cell clusters, and the functionally-closed process bioreactor system supplied the soluble nutrients and osteogenic signals required to maintain the cell viability. This system preserved the proliferative ability of cells and cell viability and up-regulated bone-related gene expression and biological apatite crystals formation. The bone-like tissue generated could be extracted by removal of calcium ions via ethylenediaminetetraacetic acid (EDTA) chelation, and exhibited a size suitable for injection. The described strategy could be used in therapeutic application and opens new avenues for surgical interventions to correct skeletal defects. PMID:25825603

  9. Alginate-chitosan coacervation in production of artificial seeds.

    PubMed

    Tay, L F; Khoh, L K; Loh, C S; Khor, E

    1993-08-05

    Survival of secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera cv. Primor) has been used as an assay for the development of artificial seeds involving complex coacervation of alginate (polyanion) with chitosan (polycation). Germination frequency of 100% was achieved for encapsulated embryoids when alginate formed the inner matrix and chitosan the outer layer. When the matrix makeup was reversed, there was no germination of embryoids. The artificial seeds produced were hardened in dilute alkaline solutions of NaOH and Ca(OH)(2). An optimum setting time could be selected based on a quantitative measurement of resistance of hardened capsules to compression and the germination frequency of the encapsulated embryoids.

  10. Alginate and Chitosan Gel Nanoparticles for Efficient Protein Entrapment

    NASA Astrophysics Data System (ADS)

    Masalova, O.; Kulikouskaya, V.; Shutava, T.; Agabekov, V.

    Alginate and chitosan nanoparticles were synthesized by ionic gelation of the polymers in the presence of stabilizers (PEG 1500, PEG 6000, TWEEN 80). The stability of 210-240 nm Ca-alginate colloids is affected by nanoparticles ageing and by the presence of a stabilizer. The diameter of chitosan nanoparticles is in the range of 180 to 260 nm and depends on polymer concentration in the reaction mixture, its molecular weight, and stabilizer type. The nanoparticles efficiently entrap a model protein, bovine serum albumin, in the amount up to 0.24 mg per 1 mg of polysaccharide.

  11. Effect of chitosan coating on a bacteria-based alginate microrobot.

    PubMed

    Park, Sung Jun; Lee, Yu Kyung; Cho, Sunghoon; Uthaman, Saji; Park, In-Kyu; Min, Jung-Joon; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2015-04-01

    To develop an efficient bacteria-based microrobot, first, therapeutic bacteria should be encapsulated into microbeads using biodegradable and biocompatible materials; second, the releasing rate of the encapsulated bacteria for theragnostic function should be regulated; and finally, flagellated bacteria should be attached on the microbeads to ensure the motility of the microrobot. For the therapeutic bacteria encapsulation, an alginate can be a promising candidate as a biodegradable and biocompatible material. Owing to the non-regulated releasing rate of the encapsulated bacteria in alginate microbeads and the weak attachment of flagellated bacteria on the surface of alginate microbeads, however, the alginate microbeads cannot be used as effective cargo for a bacteria-based microrobot. In this paper, to enhance the stability of the bacteria encapsulation and the adhesion of flagellated bacteria in alginate microbeads, we performed a surface modification of alginate microbeads using chitosan coating. The bacteria-encapsulated alginate microbeads with 1% chitosan coating maintained their structural integrity up to 72 h, whereas the control alginate microbead group without chitosan coating showed severe degradations after 24 h. The chitosan coating in alginate microbeads shows the enhanced attachment of flagellated bacteria on the surface of alginate microbeads. The bacteria-actuated microrobot with the enhanced flagellated bacteria attachment could show approximately 4.2 times higher average velocities than the control bacteria-actuated microrobot without chitosan coating. Consequently, the surface modification using chitosan coating enhanced the structural stability and the motility of the bacteria-based alginate microrobots.

  12. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    PubMed

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed.

  13. Chitosan and alginate biopolymer membranes for remediation of contaminated water with herbicides.

    PubMed

    Agostini de Moraes, Mariana; Cocenza, Daniela Sgarbi; da Cruz Vasconcellos, Fernando; Fraceto, Leonardo Fernandes; Beppu, Marisa Masumi

    2013-12-15

    This study investigated the adsorption behavior of the herbicides diquat, difenzoquat and clomazone on biopolymer membranes prepared with alginate and chitosan (pristine and multi-layer model) for contaminated water remediation applications. Herbicides, at concentrations ranging from 5 μM to 200 μM, were adsorbed in either pure alginate, pure chitosan or a bilayer membrane composed of chitosan/alginate. No adsorption of clomazone was observed on any of the membranes, probably due to lack of electrostatic interactions between the herbicide and the membranes. Diquat and difenzoquat were only adsorbed on the alginate and chitosan/alginate membranes, indicating that this adsorption takes place in the alginate layer. At a concentration of 50 μM, diquat adsorption reaches ca. 95% after 120 min on both the alginate and chitosan/alginate membranes. The adsorption of difenzoquat, at the same concentration, reaches ca. 62% after 120 min on pure alginate membranes and ca. 12% on chitosan/alginate bilayer membranes. The adsorption isotherms for diquat and difenzoquat were further evaluated using the isotherm models proposed by Langmuir and by Freundlich, where the latter represented the best-fit model. Results indicate that adsorption occurs via coulombic interactions between the herbicides and alginate and is strongly related to the electrostatic charge, partition coefficients and dissociation constants of the herbicides. Biopolymer based membranes present novel systems for the removal of herbicides from contaminated water sources and hold great promise in the field of environmental science and engineering.

  14. Microencapsulation by spray coagulation of diltiazem HCl in calcium alginate-coated chitosan.

    PubMed

    Tapia, Cristián; Montezuma, Víctor; Yazdani-Pedram, Mehrdad

    2008-01-01

    The aim of this work was to develop a procedure for encapsulation of diltiazem HCl by spray coagulation. Factors affecting the formulations such as the effect of NaCl on the solubility of diltiazem in alginate solution, surface tension, pH, viscosity of the coagulation medium, and the effect of drug load on drug release were studied. The drug load was increased substantially from 10 up to 320 mg/mL by adding 1.2% w/v NaCl in 1% w/v alginate solution. More stable microcapsules were obtained at pH 4.6 (acetate buffer) than at a pH 2.8 (lactic acid), and the microencapsulation process was favored by the type of chitosan that produced low turbidity and viscosity in the coagulation medium. A dose of 50 mg/mL of diltiazem HCl, 1.2% w/v NaCl, and chitosan CS allowed higher amount of drug to be encapsulated. The high water solubility of diltiazem HCl leads to fast release from the microcapsules.

  15. Rheological behavior and Ibuprofen delivery applications of pH responsive composite alginate hydrogels.

    PubMed

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

    2016-03-01

    Synthesis and structural characterization of hydrogels composed of sodium alginate, polyethylene oxide and acrylic acid with cyclodextrin as the hydrocolloid prepared at different pH values is presented. The hydrogels synthesized show significant variations in rheological properties, drug encapsulation capability and release kinetics. The hydrogels prepared at lower pH (pH 1) are more elastic, have high tensile strength and remain almost unaffected by varying temperature or frequency. Further, their Ibuprofen encapsulation capacity is low and releases it slowly. The hydrogel prepared at neutral pH (pH 7) is viscoelastic, thermo-reversible and also exhibits sol-gel transition on applying frequency and changing temperature. It shows highest Ibuprofen encapsulation capacity and also optimum drug release kinetics. The hydrogel prepared at higher pH (pH 12) is more viscous, has low tensile strength, is unstable to change in temperature and has fast drug release rate. The study highlights the pH responsiveness of three composite alginate hydrogels prepared under different conditions to be employed in drug delivery applications.

  16. Adsorption of arsenic by activated carbon, calcium alginate and their composite beads.

    PubMed

    Hassan, A F; Abdel-Mohsen, A M; Elhadidy, H

    2014-07-01

    The present investigation deals with preparation of three different adsorbent materials namely; potassium hydroxide activated carbon based apricot stone (C), calcium alginate beads (G) and calcium alginate/activated carbon composite beads (GC) were used for the removal of arsenic. The prepared adsorbent materials were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), N2-adsorption at -196°C and point of zero charge. From the obtained results, it was found that the porosity, surface area and total pore volume of the adsorbent material C>GC>G respectively, however, the G adsorbent has more acidic function group than the other adsorbents. The influence of pH, time, temperature and initial concentration of arsenic(V) were studied and optimized. GC exhibits the maximum As(V) adsorption (66.7mg/g at 30°C). The adsorption of arsenic ions was observed to follow pseudo-second order mechanism as well as the thermodynamic parameters confirm also the endothermic spontaneous and a physisorption process.

  17. Synthesis of photoresponsive hybrid alginate hydrogel with photo-controlled release behavior.

    PubMed

    Chiang, Chien-Ying; Chu, Chih-Chien

    2015-03-30

    A photoresponsive hybrid alginate hydrogel was successfully prepared by Ca(2+)-mediated crosslinking reaction with a mixture of β-cyclodextrin-grafted alginate (β-CD-Alg) and diazobenzene-modified poly(ethylene glycol) (Az2-PEG). The water-soluble Az2-PEG exhibits efficient trans-to-cis isomerization of the terminal azobenzene moieties under UV-light irradiation and readily switched back to the initial trans state under visible light. Because of low affinity between β-CD and cis-Az, the host-guest inclusion complex formed by β-CD and trans-Az gradually dissociates under UV-light exposure. Accordingly, the bulk gel exhibits substantial photo-induced transformation in gel morphology by the appearance of significant comb-like cavities. This photosensitive behavior accompanied by the structural degradation enables the rapid release of entrapped dye molecules under UV light stimulus. Moreover, an incident light with higher power and mild acidic environment are capable of accelerating the photo-triggered release, thus allowing the potential applications toward acute wound healing.

  18. Sodium Alginate with PEG/PEO Blends as a Floating Drug Delivery Carrier - In vitro Evaluation.

    PubMed

    Mary, Christe Sonia; Swamiappan, Sasikumar

    2016-09-01

    Purpose: Floating drug delivery system reduces the quantity of drug intake and the risk of overloading the organs with excess drug. Methods: In the present study, we prepared the blends of sodium alginate with polyethylene glycol (PEG) and polyethylene oxide (PEO) as a matrix, sodium hydrogen carbonate as a pore forming agent, methyl cellulose as a binder and barium chloride containing 10% acetic acid as a hardening agent. Different ratios of pore forming agent to the polymer blend was used to prepare the floating beads with different porosity and morphology. Ciprofloxacin hydrochloride was used as a model drug for the release kinetics studies. Results: The beads were characterized by optical and FESEM microscopy to study the morphology and pore dimensions. The results obtained shows decrease in beads size with increase in the concentration of the pore forming agent. The swelling properties of the beads were found to be in the range of 80% to 125%. The release kinetics of the ciprofloxacin from the beads was measured by UV-Visible spectroscopy at λmax of 278nm and the results shows for highly porous beads. Conclusion: By varying the amount of alginate and pore forming agent the release kinetics is found to get altered. As a result, ciprofloxacin hydrochloride release is found to be sustained from the blended beads.

  19. Novel calcium-alginate capsules with aqueous core and thermo-responsive membrane.

    PubMed

    Wang, Ji-Yun; Jin, Yao; Xie, Rui; Liu, Jie-Yi; Ju, Xiao-Jie; Meng, Tao; Chu, Liang-Yin

    2011-01-01

    Novel calcium-alginate (Ca-alginate) capsules with aqueous core and thermo-responsive membrane are successfully prepared by introducing a co-extrusion minifluidic approach, and the thermo-responsive gating characteristics of Ca-alginate capsule membranes embedded with poly(N-isopropylacrylamide) (PNIPAM) microspheres are investigated systematically. The experimental results show that the prepared Ca-alginate capsules are highly monodisperse, and the average diameter and membrane thickness of Ca-alginate capsules are about 2.96 mm and 0.11 mm respectively. The Ca-alginate capsule membranes exhibit desired thermo-responsive gating property. With increasing the content of PNIPAM microspheres embedded in the Ca-alginate capsule membranes, the thermo-responsive gating coefficient of the capsule membranes increases simply. When solute molecules diffuse through the capsule membrane, the thermo-responsive gating coefficient is significantly affected by the molecular weight of solute molecules.

  20. Comparison of a dimethicone/antacid (Asilone gel) with an alginate/antacid (Gaviscon liquid) in the management of reflux oesophagitis.

    PubMed

    Smart, H L; Atkinson, M

    1990-09-01

    Fifty-three patients with symptomatic reflux oesophagitis were entered into a single centre randomized study comparing the effects of a dimethicone/antacid (Asilone Gel) and an alginate/antacid (Gaviscon liquid) on symptoms and endoscopic changes over an 8-week period. Both treatments significantly improved heartburn, acid regurgitation and flatulence. Dimethicone/antacid but not alginate/antacid, produced a significant improvement in oesophagitis, oesophageal ulceration and histological grade of inflammation over the 8-week treatment period so that 14 patients treated with dimethicone/antacid and 10 with alginate/antacid had normal endoscopic oesophageal appearances at the end of the study. The difference in improvement between the two patient groups did not reach significance however, except for dimethicone/antacid improving histological changes (P less than 0.05). These findings suggest that dimethicone/antacid and alginate/antacid are equally effective in treating symptomatic reflux oesophagitis although dimethicone/antacid may have an advantage in improving oesophageal histological appearances.

  1. On the cellular metabolism of the click chemistry probe 19-alkyne arachidonic acid.

    PubMed

    Robichaud, Philippe Pierre; Poirier, Samuel J; Boudreau, Luc H; Doiron, Jérémie A; Barnett, David A; Boilard, Eric; Surette, Marc E

    2016-10-01

    Alkyne and azide analogs of natural compounds that can be coupled to sensitive tags by click chemistry are powerful tools to study biological processes. Arachidonic acid (AA) is a FA precursor to biologically active compounds. 19-Alkyne-AA (AA-alk) is a sensitive clickable AA analog; however, its use as a surrogate to study AA metabolism requires further evaluation. In this study, AA-alk metabolism was compared with that of AA in human cells. Jurkat cell uptake of AA was 2-fold greater than that of AA-alk, but significantly more AA-Alk was elongated to 22:4. AA and AA-alk incorporation into and remodeling between phospholipid (PL) classes was identical indicating equivalent CoA-independent AA-PL remodeling. Platelets stimulated in the pre-sence of AA-alk synthesized significantly less 12-lipoxygenase (12-LOX) and cyclooxygenase products than in the presence of AA. Ionophore-stimulated neutrophils produced significantly more 5-LOX products in the presence of AA-alk than AA. Neutrophils stimulated with only exogenous AA-alk produced significantly less 5-LOX products compared with AA, and leukotriene B4 (LTB4)-alk was 12-fold less potent at stimulating neutrophil migration than LTB4, collectively indicative of weaker leukotriene B4 receptor 1 agonist activity of LTB4-alk. Overall, these results suggest that the use of AA-alk as a surrogate for the study of AA metabolism should be carried out with caution.

  2. Immobilization of a Plant Lipase from Pachira aquatica in Alginate and Alginate/PVA Beads

    PubMed Central

    Bonine, Bárbara M.; Polizelli, Patricia Peres; Bonilla-Rodriguez, Gustavo O.

    2014-01-01

    This study reports the immobilization of a new lipase isolated from oleaginous seeds of Pachira aquatica, using beads of calcium alginate (Alg) and poly(vinyl alcohol) (PVA). We evaluated the morphology, number of cycles of reuse, optimum temperature, and temperature stability of both immobilization methods compared to the free enzyme. The immobilized enzymes were more stable than the free enzyme, keeping 60% of the original activity after 4 h at 50°C. The immobilized lipase was reused several times, with activity decreasing to approximately 50% after 5 cycles. Both the free and immobilized enzymes were found to be optimally active between 30 and 40°C. PMID:24818012

  3. Bacterial cellulose based hydrogel (BC-g-AA) and preliminary result of swelling behavior

    SciTech Connect

    Hakam, Adil; Lazim, Azwan Mat; Abdul Rahman, I. Irman

    2013-11-27

    In this study, hydrogel based on Bacterial cellulose (BC) or local known as Nata de Coco, which grafted with monomer: Acrylic acid (AA) is synthesis by using gamma radiation technique. These hydrogel (BC-g-AA) has unique characteristic whereby responsive to pH buffer solution.

  4. Alginate/polymethacrylate copolymer microparticles for the intestinal delivery of enzymes.

    PubMed

    Scocca, Sarah; Faustini, Massimo; Villani, Simona; Munari, Eleonora; Conte, Ubaldo; Russo, Vincenzo; Riccardi, Alessia; Vigo, Daniele; Torre, Maria Luisa

    2007-04-01

    Proteins administered orally must pass through the gastric environment in order to reach their site of absorption in the intestine. How to protect these exogenously administered proteins from the damaging effects of gastric acid and pepsin proteolytic activity, which often induce irreversible structural and functional alterations to the molecules, is an intriguing challenge. Another problem is the physical and chemical instability of proteins during some technological processes, which often involve the use of organic solvents or high temperatures. In this study we investigated the use of alginate microparticles containing one of two enzymes, an enteric polymer and a lyoprotectant for the intestinal delivery of proteins. The two enzymes tested in this protein delivery system were lactate dehydrogenase and alpha-amylase: the former was chosen because of its sensitivity to denaturation, the latter for its relevance in nutrition and medicine. A sodium alginate aqueous solution containing the enteric polymer, a lyoprotectant and the enzyme was either extruded or sprayed into a calcium chloride solution, with the resultant formation of beads and microspheres which were freeze-dried. About 90% of the enzyme activity was maintained during the process of loading the proteins into the microparticles and the subsequent freeze-drying process. The stability of the encapsulated enzyme in an acid medium and the enzymatic activity in an intestinal environment were then investigated by a dissolution test. This consisted of exposing the microparticles to simulated gastric fluid (pH 1.2) for 2 hours and to simulated intestinal fluid (pH 7.5+/-0.1) for 1 hour. The morphology of the microparticles did not change in the acid environment, whereas they completely dissolved within 3 min in the simulated intestinal fluid. Residual enzymatic activity after the test remained satisfactory for both enzymes. In conclusion, these microparticle systems offer promise for applications in human and

  5. Bioinspired preparation of alginate nanoparticles using microbubble bursting.

    PubMed

    Elsayed, Mohamed; Huang, Jie; Edirisinghe, Mohan

    2015-01-01

    Nanoparticles are considered to be one of the most advanced tools for drug delivery applications. In this research, alginate (a model hydrophilic polymer) nanoparticles 80 to 200 nm in diameter were obtained using microbubble bursting. The natural process of bubble bursting occurs through a number of stages, which consequently produce nano- and microsized droplets via two main production mechanisms, bubble shell disintegration and a jetting process. In this study, nano-sized droplets/particles were obtained by promoting the disintegrating mechanism and suppressing (limiting) the formation of larger microparticles resulting from the jetting mechanism. A T-junction microfluidic device was used to prepare alginate microbubbles with different sizes in a well-controlled manner. The size of the bubbles was varied by controlling two processing parameters, the solution flow rate and the bubbling pressure. Crucially, the bubble size was found to be the determining factor for inducing (or limiting) the bubble shell disintegration mechanism and the size needed to promote this process was influenced by the properties of the solution used for preparing the bubbles, particularly the viscosity. The size of alginate nanoparticles produced via the disintegration mechanism was found to be directly proportional to the viscosity of the alginate solution.

  6. Inhibition of tobramycin diffusion by binding to alginate.

    PubMed Central

    Nichols, W W; Dorrington, S M; Slack, M P; Walmsley, H L

    1988-01-01

    [3H]tobramycin bound to sodium alginate and to exopolysaccharide prepared from two mucoid strains of Pseudomonas aeruginosa. Binding to sodium alginate was similar to binding to exopolysaccharide, both in the dependence on tobramycin concentration and in the maximum binding observed at saturation. Incorporation of sodium alginate into agar plates reduced the zone sizes of growth inhibition caused by tobramycin. The reductions in zone sizes were quantitatively accounted for by the binding of tobramycin to sodium alginate during diffusion of the antibiotic away from the well in which it had been placed at the start of the experiment. However, the binding of tobramycin to the exopolysaccharide of P. aeruginosa, and the resulting inhibition of diffusion of the antibiotic, did not significantly increase the penetration time of a spherical microcolony with a radius of 125 micron, such as might be found in the respiratory tract of a patient with cystic fibrosis (from a 90% penetration time of 12 s in the absence of exopolysaccharide to one of 35 s with an exopolysaccharide concentration of 1.0% [wt/vol]). PMID:3132093

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

    PubMed

    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.

  8. Alginate Sulfate-Nanocellulose Bioinks for Cartilage Bioprinting Applications.

    PubMed

    Müller, Michael; Öztürk, Ece; Arlov, Øystein; Gatenholm, Paul; Zenobi-Wong, Marcy

    2017-01-01

    One of the challenges of bioprinting is to identify bioinks which support cell growth, tissue maturation, and ultimately the formation of functional grafts for use in regenerative medicine. The influence of this new biofabrication technology on biology of living cells, however, is still being evaluated. Recently we have identified a mitogenic hydrogel system based on alginate sulfate which potently supports chondrocyte phenotype, but is not printable due to its rheological properties (no yield point). To convert alginate sulfate to a printable bioink, it was combined with nanocellulose, which has been shown to possess very good printability. The alginate sulfate/nanocellulose ink showed good printing properties and the non-printed bioink material promoted cell spreading, proliferation, and collagen II synthesis by the encapsulated cells. When the bioink was printed, the biological performance of the cells was highly dependent on the nozzle geometry. Cell spreading properties were maintained with the lowest extrusion pressure and shear stress. However, extruding the alginate sulfate/nanocellulose bioink and chondrocytes significantly compromised cell proliferation, particularly when using small diameter nozzles and valves.

  9. Alginate Hydrogels Coated with Chitosan for Wound Dressing

    PubMed Central

    Straccia, Maria Cristina; Gomez d’Ayala, Giovanna; Romano, Ida; Oliva, Adriana; Laurienzo, Paola

    2015-01-01

    In this work, a coating of chitosan onto alginate hydrogels was realized using the water-soluble hydrochloride form of chitosan (CH-Cl), with the dual purpose of imparting antibacterial activity and delaying the release of hydrophilic molecules from the alginate matrix. Alginate hydrogels with different calcium contents were prepared by the internal setting method and coated by immersion in a CH-Cl solution. Structural analysis by cryo-scanning electron microscopy was carried out to highlight morphological alterations due to the coating layer. Tests in vitro with human mesenchymal stromal cells (MSC) were assessed to check the absence of toxicity of CH-Cl. Swelling, stability in physiological solution and release characteristics using rhodamine B as the hydrophilic model drug were compared to those of relative uncoated hydrogels. Finally, antibacterial activity against Escherichia coli was tested. Results show that alginate hydrogels coated with chitosan hydrochloride described here can be proposed as a novel medicated dressing by associating intrinsic antimicrobial activity with improved sustained release characteristics. PMID:25969981

  10. Structural Basis for Alginate Secretion Across the Bacterial Outer Membrane

    SciTech Connect

    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.

  11. Inhibition of tobramycin diffusion by binding to alginate

    SciTech Connect

    Nichols, W.W.; Dorrington, S.M.; Slack, M.P.; Walmsley, H.L.

    1988-04-01

    (/sup 3/H)tobramycin bound to sodium alginate and to exopolysaccharide prepared from two mucoid strains of Pseudomonas aeruginosa. Binding to sodium alginate was similar to binding to exopolysaccharide, both in the dependence on tobramycin concentration and in the maximum binding observed at saturation. Incorporation of sodium alginate into agar plates reduced the zone sizes of growth inhibition caused by tobramycin. The reductions in zone sizes were quantitatively accounted for by the binding of tobramycin to sodium alginate during diffusion of the antibiotic away from the well in which it had been placed at the start of the experiment. However, the binding of tobramycin to the exopolysaccharide of P. aeruginosa, and the resulting inhibition of diffusion of the antibiotic, did not significantly increase the penetration time of a spherical microcolony with a radius of 125 micron, such as might be found in the respiratory tract of a patient with cystic fibrosis (from a 90% penetration time of 12 s in the absence of exopolysaccharide to one of 35 s with an exopolysaccharide concentration of 1.0% (wt/vol)).

  12. Structural basis for alginate secretion across the bacterial outer membrane

    SciTech Connect

    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.

  13. 21 CFR 172.858 - Propylene glycol alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... additive meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 256, which is...

  14. Alginate-based ferrofluid and magnetic microsphere thereof.

    PubMed

    Xu, Peihu; Guo, Fengfeng; Huang, Jin; Zhou, Shaofeng; Wang, Daxin; Yu, Jiahui; Chen, Jinghua

    2010-12-01

    The Fe(3)O(4) ferrofluids have been prepared using sodium alginate (Na-AL) as a stabilizing agent. The alginate can prevent the aggregation of magnetic nanoparticles and hence contributed to higher stability for the ferrofluids. Furthermore, the alginate component in the ferrofluids was crosslinked by Ca(2+) to produce magnetic microspheres. The swelling behavior of magnetic microspheres showed a pH-dependence, and hence determined the drug release process under various pH conditions. The presence of the Fe(3)O(4) nanoparticles made the magnetic microspheres swell more easily. Meanwhile, the strong ability to absorb the drug for the incorporated Fe(3)O(4) nanoparticles decreased the release rate and hence was more favorable to the sustaining release of drug. Except for the controlled delivery and release of drug, the alginate-based ferrofluids and magnetic microspheres in this work might also show a great potential for other biomedical and biotechnological applications, such as, magnetic targeting, magnetic separation and magnetic resonance imaging.

  15. Alginate hydrogels coated with chitosan for wound dressing.

    PubMed

    Straccia, Maria Cristina; d'Ayala, Giovanna Gomez; Romano, Ida; Oliva, Adriana; Laurienzo, Paola

    2015-05-11

    In this work, a coating of chitosan onto alginate hydrogels was realized using the water-soluble hydrochloride form of chitosan (CH-Cl), with the dual purpose of imparting antibacterial activity and delaying the release of hydrophilic molecules from the alginate matrix. Alginate hydrogels with different calcium contents were prepared by the internal setting method and coated by immersion in a CH-Cl solution. Structural analysis by cryo-scanning electron microscopy was carried out to highlight morphological alterations due to the coating layer. Tests in vitro with human mesenchymal stromal cells (MSC) were assessed to check the absence of toxicity of CH-Cl. Swelling, stability in physiological solution and release characteristics using rhodamine B as the hydrophilic model drug were compared to those of relative uncoated hydrogels. Finally, antibacterial activity against Escherichia coli was tested. Results show that alginate hydrogels coated with chitosan hydrochloride described here can be proposed as a novel medicated dressing by associating intrinsic antimicrobial activity with improved sustained release characteristics.

  16. Proteolytic regulation of alginate overproduction in Pseudomonas aeruginosa.

    PubMed

    Damron, F Heath; Goldberg, Joanna B

    2012-05-01

    Pseudomonas aeruginosa, a Gram-negative bacterium, is a significant opportunistic pathogen associated with skin and soft tissue infections, nosocomial pneumonia and sepsis. In addition, it can chronically colonize the lungs of cystic fibrosis (CF) patients. Overproduction of the exopolysaccharide called alginate provides P. aeruginosa with a selective advantage and facilitates survival in the CF lung. The in vitro phenotype of alginate overproduction observed on solid culture media is referred to as mucoid. Expression of the alginate machinery and biosynthetic enzymes are controlled by the extracytoplasmic sigma factor, σ(22) (AlgU/T). The key negative regulator of both σ(22) activity and the mucoid phenotype is the cognate anti-sigma factor MucA. MucA sequesters σ(22) to the inner membrane inhibiting the sigma factor's transcriptional activity. The well-studied mechanism for transition to the mucoid phenotype is mutation of mucA, leading to loss of MucA function and therefore activation of σ(22) . Recently, regulated intramembrane proteolysis (RIP) has been recognized as a mechanism whereby proteolysis of the anti-sigma factor MucA leads to active σ(22) allowing P. aeruginosa to respond to environmental stress conditions by overproduction of alginate. The goal of this review is to illuminate the pathways leading to RIP that have been identified and proposed.

  17. Antioxidant properties of 2-O-beta-D-glucopyranosyl-L-ascorbic acid.

    PubMed

    Takebayashi, Jun; Yagi, Yasuyuki; Ishii, Rie; Abe, Shigeki; Yamada, Kazuhiko; Tai, Akihiro

    2008-06-01

    The antioxidant activity of a provitamin C agent, 2-O-beta-D-glucopyranosyl-L-ascorbic acid (AA-2betaG), was compared to that of 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) and ascorbic acid (AA) using four in vitro methods, 1,1-diphenyl-picrylhydrazyl (DPPH) radical-scavenging assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(*+))-scavenging assay, oxygen radical absorbance capacity (ORAC) assay, and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced erythrocyte hemolysis inhibition assay. AA-2betaG slowly and continuously scavenged DPPH radicals and ABTS(*+) in roughly the same reaction profiles as AA-2G, whereas AA quenched these radicals immediately. In the ORAC assay and the hemolysis inhibition assay, AA-2betaG showed similar overall activities to AA-2G and to AA, although the reactivity of AA-2betaG against the peroxyl radical generated in both assays was lower than that of AA-2G and AA. These data indicate that AA-2betaG had roughly the same radical-scavenging properties as AA-2G, and a comprehensive in vitro antioxidant activity of AA-2betaG appeared to be comparable not only to that of AA-2G but also to that of AA.

  18. Cold gelation of alginates induced by monovalent cations.

    PubMed

    Karakasyan, C; Legros, M; Lack, S; Brunel, F; Maingault, P; Ducouret, G; Hourdet, D

    2010-11-08

    A new reversible gelation pathway is described for alginates in aqueous media. From various samples differing by their mannuronic/guluronic content (M/G), both enthalpic and viscoelastic experiments demonstrate that alginates having a high M content are able to form thermoreversible assemblies in the presence of potassium salts. The aggregation behavior is driven by the low solubility of M-blocks at low temperature and high ionic strength. In semidilute solutions, responsive assemblies induce a strong increase of the viscosity below a critical temperature. A true physical gel is obtained in the entangled regime, although the length scale of specific interactions between M-blocks decreases with increasing density of entanglements. Cold setting takes place at low temperatures, below 0 °C for potassium concentrations lower than 0.2 mol/kg, but the aggregation process can be easily shifted to higher temperatures by increasing the salt concentration. The self-assembling process of alginates in solution of potassium salts is characterized by a sharp gelation exotherm and a broad melting endotherm with a large hysteresis of 20-30 °C between the transition temperatures. The viscoelastic properties of alginate gels in potassium salts closely depend on thermal treatment (rate of cooling, time, and temperature of storage), polymer and salt concentrations, and monomer composition as well. In the case of alginates with a high G content, a similar aggregation behavior is also evidenced at higher salt concentrations, but the extent of the self-assembling process remains too weak to develop a true gelation behavior in solution.

  19. Binding and leakage of barium in alginate microbeads.

    PubMed

    Mørch, Yrr A; Qi, Meirigeng; Gundersen, Per Ole M; Formo, Kjetil; Lacik, Igor; Skjåk-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L

    2012-11-01

    Microbeads of alginate crosslinked with Ca(2+) and/or Ba(2+) are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared with high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. To reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation.

  20. Structural insights into alginate binding by bacterial cell-surface protein.

    PubMed

    Temtrirath, Kanate; Murata, Kousaku; Hashimoto, Wataru

    2015-03-02

    A gram-negative Sphingomonas sp. strain A1 inducibly forms a mouth-like pit on the cell surface in the presence of alginate and directly incorporates polymers into the cytoplasm via the pit and ABC transporter. Among the bacterial proteins involved in import of alginate, a cell-surface EfeO-like Algp7 shows an ability to bind alginate, suggesting its contribution to accumulate alginate in the pit. Here, we show identification of its positively charged cluster involved in alginate binding using X-ray crystallography, docking simulation, and site-directed mutagenesis. The tertiary structure of Algp7 was determined at a high resolution (1.99Å) by molecular replacement, although no alginates were included in the structure. Thus, an in silico model of Algp7/oligoalginate was constructed by docking simulation using atomic coordinates of Algp7 and alginate oligosaccharides, where some charged residues were found to be potential candidates for alginate binding. Site-directed mutagenesis was conducted and five purified mutants K68A, K69A, E194A, N221A, and K68A/K69A were subjected to a binding assay. UV absorption difference spectroscopy along with differential scanning fluorimetry analysis indicated that K68A/K69A exhibited a significant reduction in binding affinity with alginate than wild-type Algp7. Based on these data, Lys68/Lys69 residues of Algp7 probably play an important role in binding alginate.

  1. In vitro evaluation of alginate/halloysite nanotube composite scaffolds for tissue engineering.

    PubMed

    Liu, Mingxian; Dai, Libing; Shi, Huizhe; Xiong, Sheng; Zhou, Changren

    2015-04-01

    In this study, a series of alginate/halloysite nanotube (HNTs) composite scaffolds were prepared by solution-mixing and freeze-drying method. HNTs are incorporated into alginate to improve both the mechanical and cell-attachment properties of the scaffolds. The interfacial interactions between alginate and HNTs were confirmed by the atomic force microscope (AFM), transmission electron microscope (TEM) and FTIR spectroscopy. The mechanical, morphological, and physico-chemical properties of the composite scaffolds were investigated. The composite scaffolds exhibit significant enhancement in compressive strength and compressive modulus compared with pure alginate scaffold both in dry and wet states. A well-interconnected porous structure with size in the range of 100-200μm and over 96% porosity is found in the composite scaffolds. X-ray diffraction (XRD) result shows that HNTs are uniformly dispersed and partly oriented in the composite scaffolds. The incorporation of HNTs leads to increase in the scaffold density and decrease in the water swelling ratio of alginate. HNTs improve the stability of alginate scaffolds against enzymatic degradation in PBS solution. Thermogravimetrica analysis (TGA) shows that HNTs can improve the thermal stability of the alginate. The mouse fibroblast cells display better attachment to the alginate/HNT composite than those to the pure alginate, suggesting the good cytocompatibility of the composite scaffolds. Alginate/HNT composite scaffolds exhibit great potential for applications in tissue engineering.

  2. Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay.

    PubMed

    Adzmi, Fariz; Meon, Sariah; Musa, Mohamed Hanafi; Yusuf, Nor Azah

    2012-01-01

    Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p < 0.05) better storage compared with room temperature (30°C).

  3. Decreased plasma arachidonic acid binding capacity in neonates.

    PubMed

    Sadowitz, P D; Walenga, R W; Clark, D; Stuart, M J

    1987-01-01

    Arachidonic acid (AA) metabolites have been implicated in neonatal pathologic states such as respiratory distress syndrome (RDS). Since free (nonprotein bound) AA is the substrate for synthesis of these compounds, a decreased capacity to bind AA in neonatal plasma could contribute to these disorders. AA binding was assayed by equilibrium dialysis in plasma samples from healthy adults and various infant groups. Plasma from these infant groups bound significantly less AA than adult plasma. Premature infants with RDS and premature infants receiving intralipid had the lowest capacity to bind AA. The increased availability of free AA may be important in neonatal pathophysiologic states involving arachidonate metabolites.

  4. Bone Regeneration Potential of Stem Cells Derived from Periodontal Ligament or Gingival Tissue Sources Encapsulated in RGD-Modified Alginate Scaffold

    PubMed Central

    Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H.; Shi, Songtao

    2014-01-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications. PMID:24070211

  5. Papain entrapment in alginate beads for stability improvement and site-specific delivery: physicochemical characterization and factorial optimization using neural network modeling.

    PubMed

    Sankalia, Mayur G; Mashru, Rajshree C; Sankalia, Jolly M; Sutariya, Vijay B

    2005-09-30

    This work examines the influence of various process parameters (like sodium alginate concentration, calcium chloride concentration, and hardening time) on papain entrapped in ionotropically cross-linked alginate beads for stability improvement and site-specific delivery to the small intestine using neural network modeling. A 3(3) full-factorial design and feed-forward neural network with multilayer perceptron was used to investigate the effect of process variables on percentage of entrapment, time required for 50% and 90% of the enzyme release, particle size, and angle of repose. Topographical characterization was conducted by scanning electron microscopy, and entrapment was confirmed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Times required for 50% (T(50)) and 90% (T(90)) of enzyme release were increased in all 3 of the process variables. Percentage entrapment and particle size were found to be directly proportional to sodium alginate concentration and inversely proportional to calcium chloride concentration and hardening time, whereas angle of repose and degree of cross-linking showed exactly opposite proportionality. Beads with >90% entrapment and T(50) of <10 minutes could be obtained at the low levels of all 3 of the process variables. The inability of beads to dissolve in acidic environment, with complete dissolution in buffer of pH >or=6.8, showed the suitability of beads to release papain into the small intestine. The shelf-life of the capsules prepared using the papain-loaded alginate beads was found to be 3.60 years compared with 1.01 years of the marketed formulation. It can be inferred from the above results that the proposed methodology can be used to prepare papain-loaded alginate beads for stability improvement and site-specific delivery.

  6. Different responses in the expression of alginases, alginate polymerase and acetylation genes during alginate production by Azotobacter vinelandii under oxygen-controlled conditions.

    PubMed

    Díaz-Barrera, Alvaro; Maturana, Nataly; Pacheco-Leyva, Ivette; Martínez, Irene; Altamirano, Claudia

    2017-02-28

    Alginate production and gene expression of genes involved in alginate biosynthesis were evaluated in continuous cultures under dissolved oxygen tension (DOT) controlled conditions. Chemostat at 8% DOT showed an increase in the specific oxygen uptake rate [Formula: see text] from 10.9 to 45.3 mmol g(-1) h(-1) by changes in the dilution rate (D) from 0.06 to 0.10 h(-1), whereas under 1% DOT the [Formula: see text] was not affected. Alginate molecular weight was not affected by DOT. However, chemostat at 1% DOT showed a downregulation up to 20-fold in genes encoding both the alginate polymerase (alg8, alg44), alginate acetylases (algV, algI) and alginate lyase AlgL. alyA1 and algE7 lyases gene expressions presented an opposite behavior by changing the DOT, suggesting that A. vinelandii can use specific depolymerases depending on the oxygen level. Overall, the DOT level have a differential effect on genes involved in alginate synthesis, thus a gene expression equilibrium determines the production of alginates of similar molecular weight under DOT controlled.

  7. Controlled and Sequential Delivery of Fluorophores from 3D Printed Alginate-PLGA Tubes.

    PubMed

    Do, Anh-Vu; Akkouch, Adil; Green, Brian; Ozbolat, Ibrahim; Debabneh, Amer; Geary, Sean; Salem, Aliasger K

    2017-01-01

    Controlled drug delivery systems, that include sequential and/or sustained drug delivery, have been utilized to enhance the therapeutic effects of many current drugs by effectively delivering drugs in a time-dependent and repeatable manner. In this study, with the aid of 3D printing technology, a novel drug delivery device was fabricated and tested to evaluate sequential delivery functionality. With an alginate shell and a poly(lactic-co-glycolic acid) (PLGA) core, the fabricated tubes displayed sequential release of distinct fluorescent dyes and showed no cytotoxicity when incubated with the human embryonic kidney (HEK293) cell line or bone marrow stromal stem cells (BMSC). The controlled differential release of drugs or proteins through such a delivery system has the potential to be used in a wide variety of biomedical applications from treating cancer to regenerative medicine.

  8. Development and in vitro characterization of insulin loaded whey protein and alginate microparticles.

    PubMed

    Déat-Lainé, Emmanuelle; Hoffart, Valérie; Cardot, Jean-Michel; Subirade, Muriel; Beyssac, Eric

    2012-12-15

    Insulin was encapsulated into microparticles (MP) made of denaturized whey proteins (WP) and alginate (ALG) using an extrusion/cold gelation process with calcium ions. High encapsulation efficiency of 85% was obtained. Influence of insulin on polymeric viscosity and on microparticle behavior was evaluated. Insulin seemed to interact with WP chains by non covalent binding and steric hindrance. This influence was balanced by ALG addition. Nevertheless, insulin was released rapidly by diffusion at both acidic and intestinal dissolution media. Despite this fast in vitro release, WP/ALG MP showed an important enzymatic inhibition effect on trypsin and alpha-chymotrypsin. Thus, WP/ALG MP contributed to an effective insulin protection towards enzymatic degradation. The aforementioned results suggested that WP based microparticles are a promising carrier for improving oral delivery of insulin.

  9. Oral sustained delivery of paracetamol from in situ-gelling gellan and sodium alginate formulations.

    PubMed

    Kubo, Wataru; Miyazaki, Shozo; Attwood, David

    2003-06-04

    The purpose of this study was to evaluate the potential for the oral sustained delivery of paracetamol of two formulations with in situ gelling properties. Oral administration of aqueous solutions of either gellan gum (1.0%, w/v) or sodium alginate (1.5%, w/v) containing calcium ions in complexed form resulted in the formation of gel depots in rabbit and rat stomachs as a consequence of the release of the calcium ions in the acidic environment. In vitro studies demonstrated diffusion-controlled release of paracetamol from the gels over a period of 6h. The bioavailability of paracetamol from the gels formed in situ in the stomachs of rabbits following oral administration of the liquid formulations was similar to that of a commercially available suspension containing an identical dose of paracetamol.

  10. Rheological investigation of the shear strength, durability, and recovery of alginate rafts formed by antacid medication in varying pH environments.

    PubMed

    Elliott, Brooke M; Steckbeck, Kathleen E; Murray, Lisa R; Erk, Kendra A

    2013-11-30

    The mechanical response of alginate rafts formed by mixing liquid alginate antacid medication (Gaviscon Extra Strength Liquid Antacid) with acidic solutions was investigated by deforming isolated rafts in a shear rheometer. As rafts were deformed to varying magnitudes of applied strain, rheological parameters were identified and related to the overall strength, durability, and recoverability of rafts formed at different pH (1.1-1.7) and aging conditions (0.5-4 h). Rafts formed in the lowest acidity solutions (pH 1.4, 1.7) were elastically weak ( G'₀ = 60 , 42 Pa for un-aged raft) yet maintained their elasticity during applied shear deformation to large values of strain (γc∼90%, 50%, where G'≈G″), and displayed a low-to-moderate level of elastic recovery following large-strain deformation. Rafts formed in the highest acidity solution had the greatest strength ( G'₀ = 500 Pa for un-aged raft and 21.5 kPa for rafts after 0.5 h of aging), reduced durability (γc∼2.5%, independent of aging), and displayed the greatest recoverability. A trade-off existed between un-aged raft strength and durability while recovery was dependent on durability, solution pH, and age. Rheometry-based evaluations of alginate rafts could be used for the informed design of future gastric retention and antacid products.

  11. Fabrication of patterned calcium cross-linked alginate hydrogel films and coatings through reductive cation exchange.

    PubMed

    Bruchet, Marion; Melman, Artem

    2015-10-20

    Calcium cross-linked alginate hydrogels are widely used in targeted drug delivery, tissue engineering, wound treatment, and other biomedical applications. We developed a method for preparing homogeneous alginate hydrogels cross-linked with Ca(2+) cations using reductive cation exchange in homogeneous iron(III) cross-linked alginate hydrogels. Treatment of iron(III) cross-linked alginate hydrogels with calcium salts and sodium ascorbate results in reduction of iron(III) cations to iron(II) that are instantaneously replaced with Ca(2+) cations, producing homogeneous ionically cross-linking hydrogels. Alternatively, the cation exchange can be performed by photochemical reduction in the presence of calcium chloride using a sacrificial photoreductant. This approach allows fabrication of patterned calcium alginate hydrogels through photochemical patterning of iron(III) cross-linked alginate hydrogel followed by the photochemical reductive exchange of iron cations to calcium.

  12. Antioxidant activity of low molecular weight alginate produced by thermal treatment.

    PubMed

    Kelishomi, Zahra Habibi; Goliaei, Bahram; Mahdavi, Hossein; Nikoofar, Alireza; Rahimi, Mahmood; Moosavi-Movahedi, Ali Akbar; Mamashli, Fatemeh; Bigdeli, Bahareh

    2016-04-01

    By definition, antioxidants are molecules that inhibit the oxidation of other molecules. Therefore, such compounds have very important clinical roles. In this study alginate polymer was depolymerized by heat treatment. The resulting low molecular weight alginates were investigated by UV-visible spectroscopy, Viscometry, Dynamic light scattering and FT-IR spectroscopy techniques. Antioxidant properties of these heat products were studied by ABTS and superoxide radical scavenging assays. Results showed that heating caused breaks in the polymer chain and so generation of low molecular weight alginates. Antioxidant measurements confirmed antioxidant activity of alginate increased upon a decrease in molecular weight. Therefore, low molecular weight alginate produced by heating could be considered as a stronger antioxidant than alginate polymer. These products could be useful for industrial and biomedical applications.

  13. Alginate gel particles-A review of production techniques and physical properties.

    PubMed

    Ching, Su Hung; Bansal, Nidhi; Bhandari, Bhesh

    2017-04-13

    The application of hydrocolloid gel particles is potentially useful in food, chemical, and pharmaceutical industries. Alginate gel particles are one of the more commonly used hydrocolloid gel particles due to them being biocompatible, nontoxic, biodegradable, cheap, and simple to produce. They are particularly valued for their application in encapsulation. Encapsulation in alginate gel particles confers protective benefits to cells, DNA, nutrients, and microbes. Slow release of flavors, minerals, and drugs can also be achieved by encapsulation in gel particles. The particle size and shape of the gel particles are crucial for specific applications. In this review, current methods of producing alginate gel particles will be discussed, taking into account their advantages, disadvantages, scalability, and impact on particle size. The physical properties of alginate gel particles will determine the effectiveness in different application conditions. This review will cover the current understanding of the alginate biopolymer, gelation mechanisms and factors affecting release properties, gel strength, and rheology of the alginate gel particle systems.

  14. Enzyme immobilization in novel alginate-chitosan core-shell microcapsules.

    PubMed

    Taqieddin, Ehab; Amiji, Mansoor

    2004-05-01

    Alginate-chitosan core-shell microcapsules were prepared in order to develop a biocompatible matrix for enzyme immobilization, where the protein is retained either in a liquid or solid core and the shell allows permeability control over substrates and products. The permeability coefficients of different molecular weight compounds (vitamin B2, vitamin B12, and myoglobin) were determined through sodium tripolyphosphate (Na-TPP)-crosslinked chitosan membrane. The microcapsule core was formed by crosslinking sodium alginate with either calcium or barium ions. The crosslinked alginate core was uniformly coated with a chitosan layer and crosslinked with Na-TPP. In the case of calcium alginate, the phosphate ions of Na-TPP were able to extract the calcium ions from alginate and liquefy the core. A model enzyme, beta-galactosidase, was immobilized in the alginate core and the catalytic activity was measured with o-nitrophenyl-beta-D-galactopyranoside (ONPG). Change in the activity of free and immobilized enzyme was determined at three different temperatures. Na-TPP crosslinked chitosan membranes were found to be permeable to solutes of up to 17,000Da molecular weight. The enzyme loading efficiency was higher in the barium alginate core (100%) as compared to the calcium alginate core (60%). The rate of ONPG conversion to o-nitrophenol was faster in the case of calcium alginate-chitosan microcapsules as compared to barium alginate-chitosan microcapsules. Barium alginate-chitosan microcapsules, however, did improve the stability of the enzyme at 37 degrees C relative to calcium alginate-chitosan microcapsules or free enzyme. This study illustrates a new method of enzyme immobilization for biotechnology applications using liquid or solid core and shell microcapsule technology.

  15. Alginate Lyase Promotes Diffusion of Aminoglycosides through the Extracellular Polysaccharide of Mucoid Pseudomonas aeruginosa

    PubMed Central

    Hatch, Richard A.; Schiller, Neal L.

    1998-01-01

    We demonstrated that a 2% suspension of Pseudomonas aeruginosa alginate completely blocked the diffusion of gentamicin and tobramycin, but not that of carbenicillin, illustrating how alginate production can help protect P. aeruginosa growing within alginate microcolonies in patients with cystic fibrosis (CF) from the effects of aminoglycosides. This aminoglycoside diffusion barrier was degraded with a semipurified preparation of P. aeruginosa alginate lyase, suggesting that this enzyme deserves consideration as an adjunctive agent for CF patients colonized by mucoid strains of P. aeruginosa. PMID:9559826

  16. Transition-metal-free synthesis of supramolecular ionic alginate-based polyurethanes.

    PubMed

    Daemi, Hamed; Barikani, Mehdi; Sardon, Haritz

    2017-02-10

    Novel high molecular weight alginate-based supramolecular ionic polyurethane (SPU) networks were prepared via the reaction of chemically modified polyanionic alginate and isocyanate-terminated cationic oligourethanes under transition-metal-free conditions. Alginate, a naturally occurring polyanionic carbohydrate diol possessing carboxylate groups, was considered as both chain extender and the anionic part of SPU network. The tailor-made, ionically crosslinked linear alginate-based SPUs illustrated superior thermal stability with a decomposition temperature around 500°C at 10% weight loss which specializes them as highly thermally stable, wonder materials compared to the today's high-tech products.

  17. Influence of Alginate on Attachment of Vibrio spp. to Stainless Steel Surfaces in Seawater

    PubMed Central

    Gordon, Andrew S.

    1987-01-01

    The influence of alginate on the attachment of Vibrio alginolyticus and Vibrio pelagius biovar II to stainless steel was investigated. When the bacteria were in stationary phase, alginate decreased the number of attached bacteria in the case of each Vibrio sp. In contrast, when V. pelagius biovar II was grown on alginate and harvested in log phase, attachment was increased. This effect may be due to nutrient availability at the surface or to receptors on the bacterial surface which interact with alginate adsorbed to the metal. PMID:16347345

  18. Alginate/bacterial cellulose nanocomposite beads prepared using Gluconacetobacter xylinus and their application in lipase immobilization.

    PubMed

    Kim, Ji Hyun; Park, Saerom; Kim, Hyungsup; Kim, Hyung Joo; Yang, Yung-Hun; Kim, Yong Hwan; Jung, Sang-Kyu; Kan, Eunsung; Lee, Sang Hyun

    2017-02-10

    Alginate/bacterial cellulose nanocomposite beads, with well-controlled size and regular spherical shapes, were prepared in a simple manner by entrapping Gluconacetobacter xylinus in barium alginate hydrogel beads, followed by cultivation of the entrapped cells in culture media with a low sodium ion concentration. The entire surface of the alginate hydrogel beads containing the cells was covered with cellulose fibers (∼30nm) after 36h of cultivation. The cellulose crystallinity index of the alginate/bacterial cellulose beads was 0.7, which was slightly lower than that of bacterial cellulose prepared by cultivating dispersed cells. The water vapor sorption capacity of the alginate/bacterial cellulose beads increased significantly from 0.07 to 38.00 (g/g dry bead) as cultivation time increased. These results clearly indicate that alginate/bacterial cellulose beads have a much higher surface area, crystallinity, and water-holding capacity than alginate beads. The immobilization of lipase on the surface of the nanocomposite beads was also investigated as a potential application of this system. The activity and specific activity of lipase immobilized on alginate/bacterial cellulose beads were 2.6- and 3.8-fold higher, respectively, than that of lipase immobilized on cellulose beads. The alginate/bacterial cellulose nanocomposite beads prepared in this study have several potential applications in the biocatalytic, biomedical, and pharmaceutical fields because of their biocompatibility, biodegradability, high crystallinity, and large surface area.

  19. Fabrication of cationic chitin nanofiber/alginate composite materials.

    PubMed

    Sato, Koki; Tanaka, Kohei; Takata, Yusei; Yamamoto, Kazuya; Kadokawa, Jun-Ichi

    2016-10-01

    We have already found that an amidinated chitin, which was prepared by the reaction of a partially deacetylated chitin with N,N-dimethylacetamide dimethyl acetal, was converted into an amidinium chitin bicarbonate with nanofiber morphology by CO2 gas bubbling and ultrasonic treatments in water. In this study, we performed the fabrication of composite materials of such cationic chitin nanofibers with an anionic polysaccharide, sodium alginate, by ion exchange. When the amidinium chitin bicarbonate nanofiber aqueous dispersion was added to an aqueous solution of sodium alginate, the composite material was agglomerated, which was isolated by centrifugation, filtration, and lyophilization, to form a manipulatable sheet. The morphology of the resulting sheet at nano-scale was evaluated by SEM measurement.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. An electrohydrodynamic bioprinter for alginate hydrogels containing living cells.

    PubMed

    Gasperini, Luca; Maniglio, Devid; Motta, Antonella; Migliaresi, Claudio

    2015-02-01

    In this work we present a bioprinting technique that exploits the electrohydrodynamic process to obtain a jet of liquid alginate beads containing cells. A printer is used to microfabricate hydrogels block by block following a bottom-up approach. Alginate beads constitute the building blocks of the microfabricated structures. The beads are placed at predefined position on a target substrate made of calcium-enriched gelatin, where they crosslink upon contact without the need of further postprocessing. The printed sample can be easily removed from the substrate at physiological temperature. Three-dimensional printing is accomplished by the deposition of multiple layers of hydrogel. We have investigated the parameters influencing the process, the compatibility of the printing procedure with cells, and their survival after printing.

  2. Rheology of mixed alginate-hyaluronan aqueous solutions.

    PubMed

    Travan, Andrea; Fiorentino, Simona; Grassi, Mario; Borgogna, Massimiliano; Marsich, Eleonora; Paoletti, Sergio; Donati, Ivan

    2015-01-01

    The present manuscript addresses the description of binary systems of hyaluronan (HA) and alginate (Alg) in semi-concentrated solution. The two polysaccharides were completely miscible in the entire range of relative weight fraction explored at a total polymer concentration of up to 3% (w/V). The rheological study encompassed steady flow and mechanical spectra for HA/Alg systems at different weight fractions with hyaluronan at different molecular weights. These extensive analyses allowed us to propose a model for the molecular arrangement in solution that envisages a mutual exclusion between the two polysaccharides even though a clear phase separation does not occur. This result may have profound implications when combinations of alginate and hyaluronan are proposed in the field of biomedical materials.

  3. Laser-assisted fabrication of highly viscous alginate microsphere

    NASA Astrophysics Data System (ADS)

    Lin, Yafu; Huang, Yong

    2011-04-01

    Encapsulated microspheres have been widely used in various biomedical applications. However, fabrication of encapsulated microspheres from highly viscous materials has always been a manufacturing challenge. The objective of this study is to explore a novel metallic foil-assisted laser-induced forward transfer (LIFT), a laser-assisted fabrication technique, to make encapsulated microspheres using high sodium alginate concentration solutions. The proposed four-layer approach includes a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a transferred suspension layer. It is found that the proposed four-layer modified LIFT approach provides a promising fabrication technology for making of bead-encapsulated microspheres from highly viscous solutions. During the process, the microsphere only can be formed if the direct-writing height is larger than the critical direct-writing height; otherwise, tail structured droplets are formed; and the encapsulated microsphere diameter linearly increases with the laser fluence and decreases with the sodium alginate concentration.

  4. Isolation of protoplasts from undaria pinnatifida by alginate lyase digestion

    NASA Astrophysics Data System (ADS)

    Xiaoke, Hu; Xiaolu, Jiang; Huashi, Guan

    2003-04-01

    The aim of this study is to isolate protoplasts from Undaria pinnatifida. Protoplasts of the alga were isolated enzymatically by using alginate lyase, which was prepared by fermenting culture of a strain Vibrio sp. 510. Monofacterial method was applied for optimizing digestion condition. The optimum condition for protoplast preparation is enzymatic digestion at 28°C for 2h using alginate lyase at the concentration of 213.36 U (8 mL) every 0.5g fresh thalline with NaCl 50 and at the shaking speed of 150 r min-1 during digestion. The protoplast yield can reach 2.62±0.09 million per 0.5 g fresh leave under the optimum condition. The enzyme activity is inhibited by Ca2+ and slightly enhanced by Fe2+ and Mn2+ at concentrations of 0.05, 0.08 and 0.10 mol L-1.

  5. Encapsulation of urease enzyme in xanthan-alginate spheres.

    PubMed

    Elçin, Y M

    1995-10-01

    Urease-containing xanthan-alginate spheres were prepared by a two-step process which involved the Ca2+ coupling of the polysaccharides, followed by gentle glutaraldehyde cross-linking with amine groups of gelatin present in the initial mixture. This second step caused a slight decrease in the enzymatic activity but increased the stability. The water content and size distribution of the spheres were examined together with the sphere morphology. The effect of polymer ratio and enzyme loading on urease activity was investigated. An increase in xanthan content was found to affect the water uptake of the spheres. Temperature and pH stability of encapsulated urease was found to be higher than the free form. The xanthan-alginate spheres showed 75% of maximum urease activity even after 20 repeated uses under optimal conditions.

  6. Immobilization of microalgae cells in alginate facilitates isolation of DNA and RNA.

    PubMed

    Lopez, Blanca R; Hernandez, Juan-Pablo; Bashan, Yoav; de-Bashan, Luz E

    2017-04-01

    Isolation of nucleic acids from Chlorella is difficult, given the chemically complex nature of their cell walls and variable production of metabolites. Immobilization of microalgae in polymers adds additional difficulty. Here, we modified, amended, and standardized methods for isolation of nucleic acids and compared the yield of DNA and RNA from free-living and encapsulated microalgae C. sorokiniana. Isolation of nucleic acids from immobilized cells required two steps in dissolving the alginate matrix, releasing the cells, and mechanical disruption with glass beads. For DNA extraction, we used modified versions of a commercial kit along with the hexadecyltrimethylammonium bromide (CTAB) method. For RNA extraction, we used the commercial TRI reagent procedure and the CTAB-dithiotreitol method. Quantity and quality of nucleic acids in extracts varied with growth conditions, isolation procedures, and time of incubation of the original culture. There were consistently higher amounts of DNA and RNA in extracts from immobilized cells. Quantitatively, the modified procedure with the commercial Promega kit was the most reliable procedure for isolating DNA and a modified commercial TRI reagent procedure was the choice for isolating RNA. All four procedures eliminated proteins efficiently and had low levels of contamination from residual polysaccharides from the matrices and/or metabolites naturally produced by the microalgae. All DNA extracts under both growth conditions, time of incubation, and two isolation methods successfully amplified the 18S ribosomal RNA by PCR and quantitative reverse transcription (RT-qPCR).

  7. [Fouling behavior of sodium alginate during microfiltration at various ionic compositions: XDLVO approach].

    PubMed

    Zhao, Ying-Xu; Zong, Rui-Qiang; Gao, Xin-Yu; Xie, Hui-Jun; Yin, Yong-Quan; Liang, Shuang

    2014-04-01

    The extended Derjaguin-Laudau-Verwey-Overbeek (XDLVO) theory was utilized to quantitatively evaluate short-range interfacial interactions involved in microfiltration (MF) membrane fouling by sodium alginate (SA) at various ionic compositions. Results showed that for hydrophilic membrane surfaces, van der Waals interactions facilitated fouling, whereas acid-base interactions alleviated fouling; for hydrophobic membrane surfaces, however, van der Waals interactions mitigated fouling and acid-base interactions turned out to be favorable for fouling. Electrostatic double layer interactions contributed minimally to fouling when SA molecules came into contact with MF membrane surface. Ionic strength and Ca2+ affected SA fouling of MF membranes mainly through alteration of acid-base interactions between membrane and SA or among SA themselves. Higher ionic strength could make acid-base interaction less repulsive or more attractive, thus aggravating SA fouling of MF membrane. Although Ca2+ accelerated flux decline significantly, Ca2+ could enhance physical cleaning efficiencies. Under all tested ionic compositions, fouling potentials (K) of initial and subsequent stages correlated well with membrane-SA interfacial free energy of adhesion and SA-SA interfacial free energy of cohesion, respectively. This implies that the XDLVO theory is applicable for description of MF membrane fouling by SA at various ionic compositions.

  8. Proteomic analysis of calcium alginate-immobilized Saccharomyces cerevisiae under high-gravity fermentation conditions.

    PubMed

    Pham, Trong Khoa; Wright, Phillip C

    2008-02-01

    Saccharomyces cerevisiae KAY446 cells immobilized in calcium alginate gel, and supplemented with additional amino acids, were successfully used in enhancing ethanol production. This combination succeeded in improving the ethanol yield and reducing the fermentation time. The ethanol yield under these conditions was 0.40 g of ethanol/g of glucose, with a final ethanol concentration of 118 g/L after 72 h. This is compared to yields with immobilized cells alone of 0.35 g of ethanol/g of glucose and freely suspended cells with no amino acid supplementation of 0.30 g of ethanol/g of glucose, under the same VHG conditions. The maximum specific ethanol production rates were 0.98, 0.73, and 0.61 g (g dry weight) (-1) h (-1) for immobilized cells under VHG conditions with and without amino acid supplementation and free cells, respectively. A proteomic analysis showed significant stimulation of many pathways during fermentation under these conditions, including the Ras/cAMP, glycolysis, starch, and sucrose pathways, amino acids biosynthesis, and aminoacyl-tRNA synthetases. The upregulation of ribosomal, heat-shock proteins and proteins involved in cell viability confirmed that protein biosynthesis was accelerated and revealed likely mechanisms for improving cellular viability.

  9. Two new plate nozzles for the production of alginate microspheres.

    PubMed

    Yang, Fan; Wang, Kang; He, Zhimin

    2005-07-14

    Combining the Rayleigh-type jet break-up and two new plate nozzles, the alginate microsphere was produced. Spray generators made of syringe needle and laser-drilling nozzle plate and synthetic red stone nozzle plate were fabricated and contrasted. The above two plate nozzles provided lower liquid resistance and yield well. Furthermore, the more uniform microsphere was produced within a wider range of frequency by plate nozzles. Experiments using multiple-nozzle synthetic red stone plate was easy to feasible.

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

    PubMed

    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.

  11. Nano zinc oxide-sodium alginate antibacterial cellulose fibres.

    PubMed

    Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Seo, Jongchul

    2016-01-01

    In the present study, antibacterial cellulose fibres were successfully fabricated by a simple and cost-effective procedure by utilizing nano zinc oxide. The possible nano zinc oxide was successfully synthesized by precipitation technique and then impregnated effectively over cellulose fibres through sodium alginate matrix. XRD analysis revealed the 'rod-like' shape alignment of zinc oxide with an interplanar d-spacing of 0.246nm corresponding to the (101) planes of the hexagonal wurtzite structure. TEM analysis confirmed the nano dimension of the synthesized zinc oxide nanoparticles. The presence of nano zinc oxide over cellulose fibres was evident from the SEM-EDS experiments. FTIR and TGA studies exhibited their effective bonding interaction. The tensile stress-strain curves data indicated the feasibility of the fabricated fibres for longer duration utility without any significant damage or breakage. The antibacterial studies against Escherichia coli revealed the excellent bacterial devastation property. Further, it was observed that when all the parameters remained constant, the variation of sodium alginate concentration showed impact in devastating the E. coli. In overall, the fabricated nano zinc oxide-sodium alginate cellulose fibres can be effectively utilized as antibacterial fibres for biomedical applications.

  12. Optimization of polyphenol oxidase immobilization in copper alginate beads.

    PubMed

    Kocaturk, Selin; Yagar, Hulya

    2010-05-01

    Polyphenol oxidase (PPO, EC 1.14.18.1) was isolated from artichoke head (Cynara scolymus L.) by using 0.1 M Tris-HCl buffer (pH 7.0), concentrated by (NH4)2SO4 precipitation, and immobilized in copper-alginate beads. Immobilization yield was determined to be 70%. The cresolase and catecholase activities of enzyme immobilized at optimum immobilization conditions were found to be 13.3 and 670 U g beads min(-1), respectively. Effects of immobilization conditions such as alginate concentration, CaCl2 concentration, amount of loading enzyme, bead size, and amount of beads on enzymatic activity were investigated. Optimum alginate and CuCl2 concentration were found to be 2 % and 3 % (w/v), respectively. Using bead (diameter 3 mm) amount of 0.25 g maximum enzyme activities were observed for both polyphenol activities. The initial concentrations of loading free enzyme were 6.5 U mL(-1) and 5815 U mL(-1) for cresolase activity and catecholase activities, respectively. Beads prepared at optimum immobilization conditions were suitable for up to 8 repeated uses.

  13. Mechanically reinforced cell-laden scaffolds formed using alginate-based bioink printed onto the surface of a PCL/alginate mesh structure for regeneration of hard tissue.

    PubMed

    Kim, Yong Bok; Lee, Hyeongjin; Yang, Gi-Hoon; Choi, Chang Hyun; Lee, DaeWeon; Hwang, Heon; Jung, Won-Kyo; Yoon, Hyeon; Kim, Geun Hyung

    2016-01-01

    Cell-printing technology has provided a new paradigm for biofabrication, with potential to overcome several shortcomings of conventional scaffold-based tissue regeneration strategies via controlled delivery of various cell types in well-defined target regions. Here we describe a cell-printing method to obtain mechanically reinforced multi-layered cell-embedded scaffolds, formed of micron-scale poly(ε-caprolactone) (PCL)/alginate struts coated with alginate-based bioink. To compare the physical and cellular activities, we used a scaffold composed of pure alginate (without cells) coated PCL/alginate struts as a control. We systematically varied the ratio of alginate cross-linking agent, and determined the optimal cell-coating conditions to form the PCL/alginate struts. Following fabrication of the cell (MG63)-laden PCL/alginate scaffold, the bioactivity was evaluated in vitro. The laden cells exhibited a substantially more developed cytoskeleton compared with those on a control scaffold consisting of the same material composition. Based on these results, the printed cells exhibited a significantly more homogenous distribution within the scaffold compared with the control. Cell proliferation was determined via MTT assays at 1, 3, 7, and 14 days of culture, and the proliferation of the cell-printed scaffold was substantially in excess (∼2.4-fold) of that on the control. Furthermore, the osteogenic activity such as ALP was measured, and the cell-laden scaffold exhibited significantly greater activity (∼3.2-fold) compared with the control scaffold.

  14. At the same hepatic amino acid load, portal infusion of amino acids is more efficient than peripheral infusion in stimulating liver protein synthesis in the dog

    PubMed Central

    Dardevet, Dominique; Kimball, Scot R; Jefferson, Leonard S; Cherrington, Alan D; Rémond, Didier; DiCostanzo, Catherine A; Moore, Mary Courtney

    2009-01-01

    Background Hepatic glucose uptake is enhanced by portal delivery of glucose which creates a negative arterio-portal substrate gradient. Hepatic amino acid (AA) utilization may be regulated by the same phenomenon, but this has not been proven. Objective We aimed to assess hepatic AA balance and protein synthesis with or without a negative arterio-portal AA gradient. Design Somatostatin was infused IV, and insulin and glucagon were replaced intraportally at 4- and 3-fold basal rates, respectively, in 3 groups (n=9 each) of conscious dogs with catheters for hepatic balance measurement. Arterial glucose concentrations were clamped at 9 mM. An AA mixture was infused IV to maintain basal concentrations (EuAA), intraportally to mimic the post-meal AA increase (PoAA), or IV (PeAA) to match the hepatic AA load in PoAA. Protein synthesis was assessed with a primed, continuous [14C]leucine infusion. Results Net hepatic glucose uptake in PoAA was ≤50% of that in EuAA and PeAA (P<0.05). The hepatic intracellular leucine concentration was 2- to 2.5-fold greater in PoAA and PeAA than EuAA (P<0.05); net hepatic leucine uptake and 14C leucine utilization were ≈2-fold greater (P<0.05) and albumin synthesis was 30% greater (P<0.05) in PoAA than EuAA and PeAA, Phosphorylation of ribosomal protein S6 (downstream of the mammalian target of Rapamycin complex 1 [mTORC1]) was significantly increased in PoAA, but not PeAA, vs EuAA. Conclusions Portal, but not peripheral, AA delivery significantly enhanced hepatic protein synthesis under conditions where AA, glucose, insulin and glucagon did not differ at the liver, an effect apparently mediated by mTORC1 signalling. PMID:18842785

  15. Improving the controlled delivery formulations of caffeine in alginate hydrogel beads combined with pectin, carrageenan, chitosan and psyllium.

    PubMed

    Belščak-Cvitanović, Ana; Komes, Draženka; Karlović, Sven; Djaković, Senka; Spoljarić, Igor; Mršić, Gordan; Ježek, Damir

    2015-01-15

    Alginate-based blends consisting of carrageenan, pectin, chitosan or psyllium husk powder were prepared for assessment of the best formulation aimed at encapsulation of caffeine. Alginate-pectin blend exhibited the lowest viscosity and provided the smallest beads. Alginate-psyllium husk blend was characterised with higher viscosity, yielding the largest bead size and the highest caffeine encapsulation efficiency (83.6%). The release kinetics of caffeine indicated that the porosity of alginate hydrogel was not reduced sufficiently to retard the diffusion of caffeine from the beads. Chitosan coated alginate beads provided the most retarded release of caffeine in water. Morphological characteristics of beads encapsulating caffeine were adversely affected by freeze drying. Bitterness intensity of caffeine-containing beads in water was the lowest for alginate-psyllium beads and chitosan coated alginate beads. Higher sodium alginate concentration (3%) for production of hydrogel beads in combination with psyllium or chitosan coating would present the most favourable carrier systems for immobilization of caffeine.

  16. Dependence of intestinal amino acid uptake on dietary protein or amino acid levels

    SciTech Connect

    Karasov, W.H.; Solberg, D.H.; Diamond, J.M.

    1987-05-01

    To understand how intestinal amino acid (AA) transport is regulated by dietary substrate levels, the authors measured uptake of seven radioactively-labelled AAs and glucose across the jejunal brush-border membrane of mice kept on one of three isocaloric rations differing in nitrogen content. In the high-protein ration, uptake increased by 77-81% for the nonessential, less toxic AAs, proline, and aspartate but only by 32-61% for the more toxic essential AAs tested. In the nitrogen-deficient ration, uptake decreased for the nonessential aspartate and proline but stayed constant or increased for essential AAs and for the nonessential alanine. These patterns imply independent regulation of the intestine's various AA transporters. With decreasing dietary AA (or protein), the imino acid and acidic AA private transporters are repressed, while activities of the basic AA transporter and the neutral AA public transporter decrease to an asymptote or else go through a minimum. These regulatory patterns can be understood as a compromise among conflicting constraints imposed by protein's multiple roles as a source of calories, nitrogen, and essential AAs and by the toxicity of essential AAs at high concentrations.

  17. AAS 227: Day 2

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-01-01

    Editors Note:This week were at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will bewritingupdates on selectedevents at themeeting and posting at the end of each day. Follow along here or atastrobites.com, or catch ourlive-tweeted updates from the@astrobites Twitter account. The usual posting schedule for AAS Nova will resumenext week.Welcome to Day 2 of the winter American Astronomical Society (AAS) meeting in Kissimmee! Several of us are attending the conference this year, and we will report highlights from each day here on astrobites. If youd like to see more timely updates during the day, we encourage you to follow @astrobites on twitter or search the #aas227 hashtag.Plenary Session: Black Hole Physics with the Event Horizon Telescope (by Susanna Kohler)If anyone needed motivation to wake up early this morning, they got it in the form of Feryal Ozel (University of Arizona) enthralling us all with exciting pictures, videos, and words about black holes and the Event Horizon Telescope. Ozel spoke to a packed room (at 8:30am!) about where the project currently stands, and where its heading in the future.The EHT has pretty much the coolest goal ever: actually image the event horizons of black holes in our universe. The problem is that the largest black hole we can look at (Sgr A*, in the center of our galaxy) has an event horizon size of 50 as. For this kind of resolution roughly equivalent to trying to image a DVD on the Moon! wed need an Earth-sized telescope. EHT has solved this problem by linking telescopes around the world, creating one giant, mm-wavelength effective telescope with a baseline the size of Earth.Besides producing awesome images, the EHT will be able to test properties of black-hole spacetime, the no-hair theorem, and general relativity (GR) in new regimes.Ozel walked us through some of the theory prep work we need to do now in order to get the most science out of the EHT, including devising new

  18. AAS 227: Day 1

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-01-01

    Editors Note:This week were at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will bewritingupdates on selectedevents at themeeting and posting at the end of each day. Follow along here or at astrobites.com, or catch ourlive-tweeted updates from the @astrobites Twitter account. The usual posting schedule for AAS Nova will resumenext week.Things kicked off last night at our undergraduate reception booth. Thanks to all of you who stopped by we were delightedto have so many people tell us that they already know about and useastrobites, and we were excited to introduce a new cohort of students at AAS to astrobites for the first time.Tuesday morning was the official start of the meeting. Here are just a few of the talks and workshops astrobiters attended today.Opening Address (by Becky Smethurst)The President of the AAS, aka our fearless leader Meg Urry kicked off the meeting this morning at the purely coffee powered hour of 8am this morning. She spoke about the importance of young astronomers at the meeting (heres looking at you reader!) and also the importance of the new Working Group for Accessibility and Disabilities (aka WGAD pronounced like wicked) at the AAS. The Society has made extra effort this year to make the conference accessible to all,a message which was very well received by everyone in attendance.Kavli Lecture: New Horizons Alan Stern (by Becky Smethurst)We were definitely spoilt with the first Plenary lecture at this years conference Alan Stern gave us a a review of the New Horizons mission of the Pluto Fly By (astrobites covered the mission back in July with this post). We were treated to beautiful images, wonderful results and a foray into geology.Before (Hubble) and after #NewHorizons. #thatisall #science #astro alanstern #aas227 pic.twitter.com/kkMt6RsSIR Science News (@topsciencething) January 5, 2016Some awesome facts from the lecture that blew my mind:New Horizons is now 2AU (!) beyond Pluto

  19. Physical and structural characteristics of acrylated poly(ethylene glycol)-alginate conjugates.

    PubMed

    Davidovich-Pinhas, Maya; Bianco-Peled, Havazelet

    2011-07-01

    Transmucosal delivery of therapeutic agents is a non-invasive approach that utilizes human entry paths such as the nasal, buccal, rectal and vaginal routes. Mucoadhesive polymers have the ability to adhere to the mucus layer covering those surfaces and by that promote drug release, targeting and absorption. We have recently demonstrated that acrylated polymers display enhanced mucoadhesive properties due to their ability to covalently attach to mucus type glycoproteins. We have synthesized an acrylated poly(ethylene glycol)-alginate conjugate (alginate-PEGAc), a molecule which combines the gelation ability of alginate with the mucoadhesion properties arising from both the characteristics of poly(ethylene glycol) and the acrylate functionality. In the current investigation we introduce an in-depth characterization of the thermal, mechanical and structural properties of alginate-PEGAc aimed at gaining a better knowledge of its structure-function relations. The thermal stability, evaluated by thermal gravimetric analysis and differential scanning calorimetry, was compared with that of alginate and the intermediate product thiolated alginate. Dehydration at temperatures up to 200 °C was detected for all samples, followed by distinctive decomposition steps arising from the decomposition of the polymer backbone and side-chains. The nanostructure of the solutions and gels was evaluated from small angle X-ray scattering patterns, to which the "broken rod linked by flexible chain" model was fitted, and from rheology measurements. The maxima arising from electrostatic repulsion between the highly charged alginate chains was diminished for both modified alginate samples, suggesting that modification led to electrostatic screening. Alginate, thiolated alginate and alginate-PEGAc cross-linked with calcium ions demonstrated similar scattering patterns. However, different scattering intensities, gel strengths, and gelation kinetics were observed, suggesting a decrease in the

  20. Oxidized alginate hydrogels for bone morphogenetic protein-2 delivery in long bone defects.

    PubMed

    Priddy, Lauren B; Chaudhuri, Ovijit; Stevens, Hazel Y; Krishnan, Laxminarayanan; Uhrig, Brent A; Willett, Nick J; Guldberg, Robert E

    2014-10-01

    Autograft treatment of large bone defects and fracture non-unions is complicated by limited tissue availability and donor site morbidity. Polymeric biomaterials such as alginate hydrogels provide an attractive tissue engineering alternative due to their biocompatibility, injectability, and tunable degradation rates. Irradiated RGD-alginate hydrogels have been used to deliver proteins such as bone morphogenetic protein-2 (BMP-2), to promote bone regeneration and restoration of function in a critically sized rat femoral defect model. However, slow degradation of irradiated alginate hydrogels may impede integration and remodeling of the regenerated bone to its native architecture. Oxidation of alginate has been used to promote degradation of alginate matrices. The objective of this study was to evaluate the effects of alginate oxidation on BMP-2 release and bone regeneration. We hypothesized that oxidized-irradiated alginate hydrogels would elicit an accelerated release of BMP-2, but degrade faster in vivo, facilitating the formation of higher quality, more mature bone compared to irradiated alginate. Indeed, oxidation of irradiated alginate did accelerate in vitro BMP-2 release. Notably, the BMP-2 retained within both constructs was bioactive at 26days, as observed by induction of alkaline phosphatase activity and positive Alizarin Red S staining of MC3T3-E1 cells. From the in vivo study, robust bone regeneration was observed in both groups through 12weeks by radiography, micro-computed tomography analyses, and biomechanical testing. Bone mineral density was significantly greater for the oxidized-irradiated alginate group at 8weeks. Histological analyses of bone defects revealed enhanced degradation of oxidized-irradiated alginate and suggested the presence of more mature bone after 12weeks of healing.

  1. Detoxification of Hg(II) from aqueous and enzyme media: Pristine vs. tailored calcium alginate hydrogels.

    PubMed

    Sarkar, Kangkana; Ansari, Zarina; Sen, Kamalika

    2016-10-01

    Calcium alginate (CA) hydrogels were tailored using phenolic compounds (PC) like, thymol, morin, catechin, hesperidin, during their preparation. The PC incorporated gels show modified surface features as indicated by scanning electron microscopic images (SEM). The rheological studies show that excepting the hesperidin incorporated gels all the other kinds including calcium alginate pristine have similar mechanical strength. The hesperidine incorporated CA gels had the maximum capacity to adsorb Hg. The Freundlich adsorption isotherms show higher values of adsorption capacity for all PC incorporated CA beads than the pristine CA (PCA). The hesperidin incorporated CA gels were found to show the best adsorption condition at neutral pH and an optimum contact time of 2.5h at 25°C. Considering the possibility of ingested Hg detoxification from human alimentary tract, the hesperidin and morin incorporated CA beads were further modified through incorporation of cod liver oil as the digestion time of fat in stomach is higher. In vitro uptake capacities of Hg in pepsin and pancreatin containing enzyme media were studied with hesperidin and morin incorporated beads and their corresponding fat incorporated beads also. In the pepsin medium, there was no uptake by hesperidin and fat-hesperidin incorporated beads, which is possibly due to the higher acidity of the medium. But in pancreatin medium Hg was taken up by both kinds of beads. Morin and morin-fat incorporated beads were efficient to uptake Hg from both the pepsin and pancreatin medium. The tailored CA beads may therefore serve as efficient scaffolds to rescue Hg ingested individuals.

  2. Efficacy of dietary arachidonic acid provided as triglyceride or phospholipid as substrates for brain arachidonic acid accretion in baboon neonates.

    PubMed

    Wijendran, Vasuki; Huang, Meng-Chuan; Diau, Guan-Yeu; Boehm, Günther; Nathanielsz, Peter W; Brenna, J Thomas

    2002-03-01

    Arachidonic acid (AA) is a long-chain polyunsaturate (LCP) present in human breast milk as both triglyceride (TG) and as phospholipid (PL). There has been little attention to the metabolic consequences of lipid form of AA in infant formulas. Our objective was to investigate the efficacy of dietary TG and PL as carriers of AA for accretion in the brain and associated organs of term baboon neonates consuming a formula with LCP composition typical of human milk. TG and phosphatidylcholine (PC) with [U-(13)C]-AA in the sn-2 position and with unlabeled 16:0 in the remaining positions (TG-AA* or PL-AA*, respectively) were used as tracers to study the tissue AA* incorporation. Baboon neonates received a single oral dose of either TG-AA* (n = 3) or PL-AA* (n = 4) at 18-19 d of life. Tissues were obtained 10 d later (28-29 d of life) and isotopic enrichment was measured. In the brain, 4.5% of the PL-AA* dose and 2.1% of the TG-AA* dose were recovered as brain AA*, respectively, indicating that PL was about 2.1-fold more effective than TG as a substrate for brain AA accretion. Preferential incorporation of PL-derived AA* over TG source of AA* was also observed in the liver, lung, plasma, and erythrocytes. Because of the quantitative predominance of TG-AA in formula, total brain AA accretion, expressed as absolute weight, was 5.0-fold greater from TG-AA than from PL-AA. We estimate that about half of postnatal brain AA accretion is derived from dietary preformed AA in term baboon neonates consuming a formula with lipid composition similar to that of human milk.

  3. Encapsulation in alginate and alginate coated-chitosan improved the survival of newly probiotic in oxgall and gastric juice.

    PubMed

    Trabelsi, Imen; Bejar, Wacim; Ayadi, Dorra; Chouayekh, Hichem; Kammoun, Radhouane; Bejar, Samir; Ben Salah, Riadh

    2013-10-01

    This study was undertaken to develop an optimum composition model for the microencapsulation of a newly probiotic on sodium alginate using response surface methodology. The individual and interactive effects of three independent variables, namely sodium alginate concentration, biomass concentration, and hardening time, were investigated using Box-Behnken design experiments. A second ordered polynomial model was fitted and optimum conditions were estimated. The optimal conditions identified were 2% for sodium alginate, 10(10)UFC/ml for biomass, and 30 min for hardening time. The experimental value obtained for immobilized cells under these conditions was about 80.98%, which was in close agreement with the predicted value of 82.6%. Viability of microspheres (96%) was enhanced with chitosan as coating materials. The survival rates of free and microencapsulated Lactobacillus plantarum TN8 during exposure to artificial gastrointestinal conditions were compared. The results revealed that the encapsulated cells exhibited significantly higher resistances to artificial intestinal juice (AIJ) and artificial gastric juice (AGJ). Microencapsulation was also noted to effectively protect the strain from heating at 65 °C and refrigerating at 4 °C. Taken together, the findings indicated that microencapsulation conferred important protective effects to L. plantarum against the gastrointestinal conditions encountered during the transit of food.

  4. Effect of various gelling cations on the physical properties of "wet" alginate films.

    PubMed

    Harper, B Allison; Barbut, Shai; Lim, Loong-Tak; Marcone, Massimo F

    2014-04-01

    In this study, the physical properties of "wet" alginate films gelled with various divalent cations (Ba(2+) , Ca(2+) , Mg(2+) , Sr(2+) , and Zn(2+) ) were explored. Additionally, the effect of adding NaCl to the alginate film-forming solution prior to gelling was evaluated. Aside from Mg(2+) , all of the divalent cations were able to produce workable "wet" alginate films. Films gelled with BaCl2 (without added NaCl) had the highest (P < 0.05) tensile strength and Young's modulus while films gelled with CaCl2 (alone) had the highest puncture strength. The Zn-alginate and Sr-alginate films had the highest elongation at break values. Adding NaCl to the alginate film-forming solution increased the viscosity of the solution. Films with added NaCl were less transparent and had lower tensile strength, elongation, and puncture strength than films formed without NaCl in the film-forming solution. ATR-FTIR results showed a slight shift in the asymmetric COO(-) vibrational peak of the alginate when the "wet" alginate films were gelled with Zn(2+) .

  5. Interpenetrated Si-HPMC/alginate hydrogels as a potential scaffold for human tissue regeneration.

    PubMed

    Viguier, Alexia; Boyer, Cecile; Chassenieux, Christophe; Benyahia, Lazhar; Guicheux, Jérôme; Weiss, Pierre; Rethore, Gildas; Nicolai, Taco

    2016-05-01

    Interpenetrated gels of biocompatible polysaccharides alginate and silanized hydroxypropyl methyl cellulose (Si-HPMC) have been studied in order to assess their potential as scaffolds for the regeneration of human tissues. Si-HPMC networks were formed by reduction of the pH to neutral and alginate networks were formed by progressive in situ release of Ca(2+). Linear and non-linear mechanical properties of the mixed gels at different polymer and calcium concentrations were compared with those of the corresponding single gels. The alginate/Si-HPMC gels were found to be stiffer than pure Si-HPMC gels, but weaker and more deformable than pure alginate gels. No significant difference was found for the maximum stress at rupture measured during compression for all these gels. The degrees of swelling or contraction in excess water at pH 7 as well as the release of Ca(2+) was measured as a function of time. Pure alginate gels contracted by as much as 50 % and showed syneresis, which was much reduced or even eliminated for mixed gels. The important release of Ca(2+) upon ageing for pure alginate gels was much reduced for the mixed gels. Furthermore, results of cytocompatibility assays indicated that there was no cytotoxicity of Si-HPMC/alginate hydrogels in 2D and 3D culture of human SW1353 cells. The results show that using interpenetrated Si-HPMC/alginate gels has clear advantages over the use of single gels for application in tissue regeneration.

  6. Alginate as a cell culture substrate for growth and differentiation of human retinal pigment epithelial cells.

    PubMed

    Heidari, Razeih; Soheili, Zahra-Soheila; Samiei, Shahram; Ahmadieh, Hamid; Davari, Maliheh; Nazemroaya, Fatemeh; Bagheri, Abouzar; Deezagi, Abdolkhalegh

    2015-03-01

    The purpose of this study was to evaluate retinal pigment epithelium (RPE) cells' behavior in alginate beads that establish 3D environment for cellular growth and mimic extracellular matrix versus the conventional 2D monolayer culture. RPE cells were encapsulated in alginate beads by dripping alginate cell suspension into CaCl2 solution. Beads were suspended in three different media including Dulbecco's modified Eagle's medium (DMEM)/F12 alone, DMEM/F12 supplemented with 10 % fetal bovine serum (FBS), and DMEM/F12 supplemented with 30 % human amniotic fluid (HAF). RPE cells were cultivated on polystyrene under the same conditions as controls. Cell phenotype, cell proliferation, cell death, and MTT assay, immunocytochemistry, and real-time RT-PCR were performed to evaluate the effect of alginate on RPE cells characteristics and integrity. RPE cells can survive and proliferate in alginate matrixes. Immunocytochemistry analysis exhibited Nestin, RPE65, and cytokeratin expressions in a reasonable number of cultured cells in alginate beads. Real-time PCR data demonstrated high levels of Nestin, CHX10, RPE65, and tyrosinase gene expressions in RPE cells immobilized in alginate when compared to 2D monolayer culture systems. The results suggest that alginate can be used as a reliable scaffold for maintenance of RPE cells' integrity and in vitro propagation of human retinal progenitor cells for cell replacement therapies in retinal diseases.

  7. Comparative investigation of the binding characteristics of poly-L-lysine and chitosan on alginate hydrogel.

    PubMed

    Ren, Ying; Xie, Hongguo; Liu, Xiaocen; Bao, Jie; Yu, Weiting; Ma, Xiaojun

    2016-03-01

    The binding properties of poly-L-lysine and chitosan to alginate have been evaluated quantitatively and compared. Poly-L-lysine bound to alginate hydrogel more rapidly than chitosan as poly-L-lysine has a smaller molar hydrodynamic volume. In addition, poly-L-lysine showed a much higher binding capacity (6.14:1) for alginate hydrogel beads than chitosan (2.71:1), and a little higher binding stoichiometry (0.58) to sodium alginate molecules in solution than chitosan (0.49). An exothermic heat of alginate-poly-L-lysine complexes formation of 2.02 kJ/mol was detected. For alginate-chitosan complexes, the binding enthalpy has been seen to be -3.49 kJ/mol. The stability of the polyelectrolyte complexes was related to their binding enthalpy. The alginate-poly-L-lysine complexes could be disintegrated and rebuilt. By contrast, chitosan was bound with alginate in a steady state. These results provide fundamental insights regarding the structure and property relationships of macromolecules, and will be helpful in designing and selecting appropriate polymers.

  8. Three-dimensional Alginate-bead Culture of Human Pituitary Adenoma Cells.

    PubMed

    Avila-Rodríguez, Dulce; Paisano-Cerón, Karina; Valdovinos-Ramírez, Irene; Solano-Agama, Carmen; Ortiz-Plata, Alma; Mendoza-Garrido, María E

    2016-02-18

    A three-dimensional culture method is described in which primary pituitary adenoma cells are grown in alginate beads. Alginate is a polymer derived from brown sea algae. Briefly, the tumor tissue is cut into small pieces and submitted to an enzymatic digestion with collagenase and trypsin. Next, a cell suspension is obtained. The tumor cell suspension is mixed with 1.2% sodium alginate and dropped into a CaCl2 solution, and the alginate/cell suspension is gelled on contact with the CaCl2 to form spherical beads. The cells embedded in the alginate beads are supplied with nutrients provided by the culture media enriched with 20% FBS. Three-dimensional culture in alginate beads maintains the viability of adenoma cells for long periods of time, up to four months. Moreover, the cells can be liberated from the alginate by washing the beads with sodium citrate and seeded on glass coverslips for further immunocytochemical analyses. The use of a cell culture model allows for the fixation and visualization of the actin cytoskeleton with minimal disorganization. In summary, alginate beads provide a reliable culture system for the maintenance of pituitary adenoma cells.

  9. Surfactant and metal ion effects on the mechanical properties of alginate hydrogels.

    PubMed

    Kaygusuz, Hakan; Evingür, Gülşen Akın; Pekcan, Önder; von Klitzing, Regine; Erim, F Bedia

    2016-11-01

    This paper addresses the controlled variation of the mechanical properties of alginate gel beads by changing the alginate concentration or by adding different surfactants or cross-linking cations. Alginate beads containing nonionic Brij 35 or anionic sodium dodecyl sulfate (SDS) surfactants were prepared with two different types of cations (Ca(2+), Ba(2+)) as crosslinkers. Compression measurements were performed to investigate the effect of the surfactant and cation types and their concentrations on the Young's modulus of alginate beads. The Young's modulus was determined by using Hertz theory. For all types of alginate gel beads the Young's modulus showed an increasing value for increasing alginate contents. Addition of the anionic surfactant SDS increases the Young's modulus of the alginate beads while the addition of non-ionic surfactant Brij 35 leads to a decrease in Young's modulus. This opposite behavior is related to the contrary effect of both surfactants on the charge of the alginate beads. When Ba(2+) ions were used as crosslinker cation, the Young's modulus of the beads with the surfactant SDS was found to be approximately two times higher than the modulus of beads with the surfactant Brij 35. An ion specific effect was found for the crosslinking ability of divalent cations.

  10. Screening of alginate lyase-excreting microorganisms from the surface of brown algae.

    PubMed

    Wang, Mingpeng; Chen, Lei; Zhang, Zhaojie; Wang, Xuejiang; Qin, Song; Yan, Peisheng

    2017-12-01

    Alginate lyase is a biocatalyst that degrades alginate to produce oligosaccharides, which have many bioactive functions and could be used as renewable biofuels. Here we report a simple and sensitive plate assay for screening alginate lyase-excreting microorganisms from brown algae. Brown algae Laminaria japonica, Sargassum horneri and Sargassum siliquatrum were cultured in sterile water. Bacteria growing on the surface of seaweeds were identified and their capacity of excreting alginate lyase was analyzed. A total of 196 strains were recovered from the three different algae samples and 12 different bacterial strains were identified capable of excreting alginate lyases. Sequence analysis of the 16S rRNA gene revealed that these alginate lyase-excreting strains belong to eight genera: Paenibacillus (4/12), Bacillus (2/12), Leclercia (1/12), Isoptericola (1/12), Planomicrobium (1/12), Pseudomonas (1/12), Lysinibacillus (1/12) and Sphingomonas (1/12). Further analysis showed that the LJ-3 strain (Bacillus halosaccharovorans) had the highest enzyme activity. To our best knowledge, this is the first report regarding alginate lyase-excreting strains in Paenibacillus, Planomicrobium and Leclercia. We believe that our method used in this study is relatively easy and reliable for large-scale screening of alginate lyase-excreting microorganisms.

  11. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism.

    PubMed

    Horniblow, Richard D; Dowle, Miriam; Iqbal, Tariq H; Latunde-Dada, Gladys O; Palmer, Richard E; Pikramenou, Zoe; Tselepis, Chris

    2015-01-01

    Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease.

  12. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism

    PubMed Central

    Horniblow, Richard D.; Dowle, Miriam; Iqbal, Tariq H.; Latunde-Dada, Gladys O.; Palmer, Richard E.

    2015-01-01

    Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease. PMID:26378798

  13. Laponite as a rheology modifier of alginate solutions: Physical gelation and aging evolution.

    PubMed

    Dávila, José Luis; d'Ávila, Marcos Akira

    2017-02-10

    The rheological behavior of alginate and Laponite/alginate solutions was studied. It was observed that the Cross viscosity model successfully describes the steady-state shear behavior of this polysaccharide. The scaling behavior analyzed for the entangled regime is in good agreement with polyelectrolyte solutions (Ge∼cp(3/2)), with interactions generated between the alginate and the charged surfaces of the Laponite platelets. Therefore, the effect of Laponite as a rheology modifier is influenced by the alginate concentration. Higher alginate concentrations hindered the formation of the house of cards microstructure. Frequency sweep tests were performed to analyze the transition from solid-like to liquid-like behavior in a solid-like dominated domain. Soft physical gels were obtained at low alginate concentrations. The gel point was determined (1.65wt.% of alginate and 2wt.% of Laponite) through the Kramers-Krönig damping factor, and time sweep tests revealed the evolution of the storage (G') and loss modulus (G″) as functions of the waiting time (tw). The growing elasticity revealed that Laponite/alginate solutions undergo aging.

  14. Human neutrophil elastase inhibition with a novel cotton alginate wound dressing formulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Occlusion and elasticity were combined in a novel cotton-based alginate dressing containing a non-toxic elastase inhibitor. Cotton gauzes were modified with a textile finishing process for incorporating alginate to yield a dressing material that retains elasticity while enhancing absorption. The ...

  15. Bacterial pyruvate production from alginate, a promising carbon source from marine brown macroalgae.

    PubMed

    Kawai, Shigeyuki; Ohashi, Kazuto; Yoshida, Shiori; Fujii, Mari; Mikami, Shinichi; Sato, Nobuyuki; Murata, Kousaku

    2014-03-01

    Marine brown macroalgae is a promising source of material for biorefining, and alginate is one of the major components of brown algae. Despite the huge potential availability of alginate, no system has been reported for the production of valuable compounds other than ethanol from alginate, hindering its further utilization. Here we report that a bacterium, Sphingomonas sp. strain A1, produces pyruvate from alginate and secretes it into the medium. High aeration and deletion of the gene for d-lactate dehydrogenase are critical for the production of high concentrations of pyruvate. Pyruvate concentration and productivity were at their maxima (4.56 g/l and 95.0 mg/l/h, respectively) in the presence of 5% (w/v) initial alginate, whereas pyruvate produced per alginate consumed and % of theoretical yield (0.19 g/g and 18.6%, respectively) were at their maxima at 4% (w/v) initial alginate. Concentration of pyruvate decreased after it reached its maximum after cultivations for 2 or 3 days at 145 strokes per minute. Our study is the first report to demonstrate the production of other valuable compounds than ethanol from alginate, a promising marine macroalgae carbon source.

  16. Three alginate lyases from marine bacterium Pseudomonas fluorescens HZJ216: purification and characterization.

    PubMed

    Li, Liyan; Jiang, Xiaolu; Guan, Huashi; Wang, Peng; Guo, Hong

    2011-06-01

    Three alginate lyases (A, B, and C) from an alginate-degrading marine bacterium strain HZJ216 isolated from brown seaweed in the Yellow Sea of China and identified preliminarily as Pseudomonas fluorescens are purified, and their biochemical properties are described. Molecular masses of the three enzymes are determined by SDS-PAGE to be 60.25, 36, and 23 kDa with isoelectric points of 4, 4.36, and 4.59, respectively. Investigations of these enzymes at different pH and temperatures show that they are most active at pH 7.0 and 35 °C. Alginate lyases A and B are stable in the pH range of 5.0-9.0, while alginate lyase C is stable in the pH range of 5.0-7.0. Among the metal ions tested, additions of Na(+), K(+), and Mg(2+) ions can enhance the enzyme activities while Fe(2+), Fe(3+), Ba(2+), and Zn(2+) ions show inhibitory effects. The substrate specificity results demonstrate that alginate lyase C has the specificity for G block while alginate lyases A and B have the activities for both M and G blocks. It is the first report about extracellular alginate lyases with high alginate-degrading activity from P. fluorescens.

  17. Jellyfish collagen and alginate: Combined marine materials for superior chondrogenesis of hMSC.

    PubMed

    Pustlauk, W; Paul, B; Gelinsky, M; Bernhardt, A

    2016-07-01

    Marine, hybrid constructs of porous scaffolds from fibrillized jellyfish collagen and alginate hydrogel are mimicking both of the main tissue components of cartilage, thus being a promising approach for chondrogenic differentiation of human mesenchymal stem cells (hMSC). Investigating their potential for articular cartilage repair, the present study examined scaffolds being either infiltrated with an alginate-cell-suspension (ACS) or seeded with hMSC and embedded in alginate after cell adhesion (EAS). Hybrid constructs with 2×10(5) and 4.5×10(5)hMSC/scaffold were compared to hMSC encapsulated in pure alginate discs, both chondrogenically stimulated for 21days. Typical round, chondrocyte-like morphology was observed in pure alginate gels and ACS scaffolds, while cells in EAS were elongated and tightly attached to the collagen pores. Col 2 gene expression was comparable in all scaffold types examined. However, the Col 2/Col 1 ratio was higher for pure alginate discs and ACS scaffolds compared to EAS. In contrast, cells in EAS scaffolds displayed higher gene expression of Sox 9, Col 11 and ACAN compared to ACS and pure alginate. Secretion of sulfated glycosaminoglycans (sGAG) was comparable for ACS and EAS scaffolds. In conclusion hybrid constructs of jellyfish collagen and alginate support hMSC chondrogenic differentiation and provide more stable and constructs compared to pure hydrogels.

  18. Three Alginate Lyases from Marine Bacterium Pseudomonas fluorescens HZJ216: Purification and Characterization

    SciTech Connect

    Liyan, Li; Jiang, Xiaolu; Wang, Peng; Guan, Huashi; Guo, Hong

    2010-01-01

    Three alginate lyases (A, B, and C) from an alginate-degrading marine bacterium strain HZJ216 isolated from brown seaweed in the Yellow Sea of China and identified preliminarily as Pseudomonas fluorescens are purified, and their biochemical properties are described. Molecular masses of the three enzymes are determined by SDS-PAGE to be 60.25, 36, and 23 kDa with isoelectric points of 4, 4.36, and 4.59, respectively. Investigations of these enzymes at different pH and temperatures show that they are most active at pH 7.0 and 35 C. Alginate lyases A and B are stable in the pH range of 5.0 9.0, while alginate lyase C is stable in the pH range of 5.0 7.0. Among the metal ions tested, additions of Na+, K+, and Mg2+ ions can enhance the enzyme activities while Fe2+, Fe3+, Ba2+, and Zn2+ ions show inhibitory effects. The substrate specificity results demonstrate that alginate lyase C has the specificity for G block while alginate lyases A and B have the activities for both M and G blocks. It is the first report about extracellular alginate lyases with high alginate-degrading activity from P. fluorescens.

  19. AAS 227: Day 3

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-01-01

    Editors Note:This week were at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will bewritingupdates on selectedevents at themeeting and posting at the end of each day. Follow along here or atastrobites.com, or catch ourlive-tweeted updates from the@astrobites Twitter account. The usual posting schedule for AAS Nova will resumenext week.Welcome to Day 3 of the winter American Astronomical Society (AAS) meeting in Kissimmee! Several of us are attending the conference this year, and we will report highlights from each day here on astrobites. If youd like to see more timely updates during the day, we encourage you to follow @astrobites on twitter or search the #aas227 hashtag.Henry Norris Russell Lecture: Viewing the Universe with Infrared Eyes: The Spitzer Space Telescope (by Erika Nesvold)The Henry Norris Russell Award is the highest honor given by the AAS, for a lifetime of eminence in astronomy research. This years award went to Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. Fazio became a leader in gamma ray astronomy before switching mid-career to the study of infrared astronomy, and he gave his award lecture on the latter subject, specifically on the Spitzer Space Telescope, one of the most successful infrared telescopes of all time.Artists rendering of the Spitzer space telescope. [NASA/JPL-Caltech]Spitzer has been operating for more than twelve years, and has resulted in over six thousand papers in refereed journals in that time. The telescope sits in an Earth-trailing orbit around the Sun, and is now farther from the Earth (1.4 AU) than the Earth is from the Sun. Fazio gave the audience a fascinating overview of the science done by Spitzer over more than a decade. One of the most productive areas of research for Spitzer is the study of exoplanets, which hadnt even been discovered when the Spitzer Telescope was first conceived. Spitzers high sensitivity and ability to observe exoplanets over

  20. A rapid, sensitive, simple plate assay for detection of microbial alginate lyase activity.

    PubMed

    Sawant, Shailesh S; Salunke, Bipinchandra K; Kim, Beom Soo

    2015-09-01

    Screening of microorganisms capable of producing alginate lyase enzyme is commonly carried out by investigating their abilities to grow on alginate-containing solid media plates and occurrence of a clearance zone after flooding the plates with agents such as 10% (w/v) cetyl pyridinium chloride (CPC), which can form complexes with alginate. Although the CPC method is good, advantageous, and routinely used, the agar in the media interferes with the action of CPC, which makes judgment about clearance zones very difficult. In addition, this method takes a minimum of 30 min to obtain the zone of hydrolysis after flooding and the hydrolyzed area is not sharply discernible. An improved plate assay is reported herein for the detection of extracellular alginate lyase production by microorganisms. In this method, alginate-containing agar plates are flooded with Gram's iodine instead of CPC. Gram's iodine forms a bluish black complex with alginate but not with hydrolyzed alginate, giving sharp, distinct zones around the alginate lyase producing microbial colonies within 2-3 min. Gram's iodine method was found to be more effective than the CPC method in terms of visualization and measurement of zone size. The alginate-lyase-activity area indicated using the Gram's iodine method was found to be larger than that indicated by the CPC method. Both methods (CPC and Gram's iodine) showed the largest alginate lyase activity area for Saccharophagus degradans (ATCC 43961) followed by Microbulbifer mangrovi (KCTC 23483), Bacillus cereus (KF801505) and Paracoccus sp. LL1 (KP288668) grown on minimal sea salt medium. The rate of growth and metabolite production in alginate-containing minimal sea salt liquid medium, followed trends similar to that of the zone activity areas for the four bacteria under study. These results suggested that the assay developed in this study of Gram's iodine could be useful to predict the potential of microorganisms to produce alginate lyase. The method also

  1. Investigation of alginate binding to germanium and polystyrene substrata conditioned with mussel adhesive protein

    SciTech Connect

    Suci, P.A.; Geesey, G.G.

    1995-06-15

    Binding of alginate from Macrocystis pyrifera (kelp) to germanium and polystyrene substrata conditioned with mussel adhesive protein (MAP) from Mytilis edulis, to germanium substrata conditioned with bovine serum albumin (BSA) and polylysine, and to germanium substrata coated with aminopropyltriethoxysilane (APS) was investigated using attenuated total reflection Fourier transform infrared spectrometry. Binding of alginate to MAP appears to be proportional to surface coverage for levels tested. Distinct spectral features appear in the region associated with pyranose ring vibrations upon binding of alginate to MAP, polylysine, and APS, indicating that lysine residues play a prominent role in promoting irreversible adsorption with perturbation of pyranose ring atoms. BSA does not appear to enhance alginate adsorption over that observed on clean germanium and no new spectral features appear as a result of binding. The level of irreversible binding of alginate to germanium and polystyrene substrata conditioned with MAP is similar.

  2. Development and physicochemical characterization of alginate composite film loaded with simvastatin as a potential wound dressing.

    PubMed

    Rezvanian, Masoud; Amin, Mohd Cairul Iqbal Mohd; Ng, Shiow-Fern

    2016-02-10

    Previously, studies have demonstrated that topical application of simvastatin can promote wound healing in diabetic mice via augmentation of angiogenesis and lymphangiogenesis. This study aimed to formulate and characterize simvastatin in alginate-based composite film wound dressings. Biopolymers used for composite films were sodium alginate blended with pectin or gelatin. The films were prepared and characterized based on their physical properties, surface morphology, mechanical strength and rheology. Then, in vitro drug releases from the films were investigated and, finally, the cell viability assay was performed to assess the cytotoxicity profile. From the pre-formulation studies, alginate/pectin composite film showed to possess desirable wound dressing properties and superior mechanical properties. The in vitro drug release profile revealed that alginate/pectin film produced a controlled release drug profile, and cell viability assay showed that the film was non-toxic. In summary, alginate/pectin composite film is suitable to be formulated with simvastatin as a potential wound dressing.

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

    NASA Astrophysics Data System (ADS)

    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*).

  4. Alginate-polymethacrylate hybrid hydrogels with double ionic and covalent network for tissue engineering

    NASA Astrophysics Data System (ADS)

    Schizzi, I.; Utzeri, R.; Castellano, M.; Stagnaro, P.

    2016-05-01

    Hydrogels based on alginates are very promising candidates to realize scaffolds for tissue engineering. Indeed, alginate hydrogels are able to mimic the extracellular matrix (ECM) thus promoting in vitro and/or in vivo cell growth; moreover, their capability of giving rise to highly porous structures can specifically favor the osteochondral tissue regeneration. However, mechanical properties of polymeric hydrogels are often inadequate to endow the final constructs with the required characteristics of elasticity and toughness. Here alginate/polymethacrylate hybrid hydrogels, with a suitable porous structure and characterized by a double network, ionic (from alginate) and covalent (from polymethacrylate) were designed and realized. The mechanical performance of these hybrid materials resulted, as expected, improved due to the double interconnected network, where the alginate portion provides the appropriate micro-environment mimicking the ECM, whereas the polymethacrylate portion acts as a reinforce.

  5. Microencapsulation of bioactives in cross-linked alginate matrices by spray drying.

    PubMed

    Santa-Maria, Monica; Scher, Herbert; Jeoh, Tina

    2012-01-01

    Microencapsulation of biomolecules, cells and chemicals is widely used in the food and pharmaceutical industries to improve stability, delivery and to control the release of encapsulated moieties. Among encapsulation matrices, alginate is preferred due to its low cost, biodegradability and biocompatibility. Current methods for producing stable alginate gels involve dropping alginate suspensions into divalent cation solutions. This procedure is difficult to scale-up and produces undesirably large alginate beads. In our novel encapsulation method, alginate gelation occurs during spray drying upon volatilisation of a base and rapid release of otherwise unavailable calcium ions. The resulting particles, with median particle sizes in the range 15-120 µm, are insoluble in solution. Cellulase and hemicellulase activities encapsulated by this method were not compromised during spray drying and remained stable over prolonged storage. The procedure described here offers a one-step alternative to other encapsulation methods that are costly and difficult to scale-up.

  6. Innovative plasticized alginate obtained by thermo-mechanical mixing: Effect of different biobased polyols systems.

    PubMed

    Gao, Chengcheng; Pollet, Eric; Avérous, Luc

    2017-02-10

    Plasticized alginate films with different biobased polyols (glycerol and sorbitol) and their mixtures were successfully prepared by thermo-mechanical mixing instead of the usual casting-evaporation procedure. The microstructure and properties of the different plasticized alginate formulations were investigated by SEM, FTIR, XRD, DMTA and uniaxial tensile tests. SEM and XRD results showed that native alginate particles were largely destructured with the plasticizers (polyols and water), under a thermo-mechanical input. With increasing amount of plasticizers, the samples showed enhanced homogeneity while their thermal and mechanical properties decreased. Compared to sorbitol, glycerol resulted in alginate films with a higher flexibility due to its better plasticization efficiency resulting from its smaller size and higher hydrophilic character. Glycerol and sorbitol mixtures seemed to be an optimum to obtain the best properties. This work showed that thermo-mechanical mixing is a promising method to produce, at large scale, plasticized alginate-based films with improved properties.

  7. Polydopamine-Mediated Immobilization of Alginate Lyase to Prevent P. aeruginosa Adhesion.

    PubMed

    Alves, Diana; Sileika, Tadas; Messersmith, Phillip B; Pereira, Maria Olívia

    2016-09-01

    Given alginate's contribution to Pseudomonas aeruginosa virulence, it has long been considered a promising target for interventional therapies, which have been performed by using the enzyme alginate lyase. In this work, instead of treating pre-established mucoid biofilms, alginate lyase is immobilized onto a surface as a preventive measure against P. aeruginosa adhesion. A polydopamine dip-coating strategy is employed for functionalization of polycarbonate surfaces. Enzyme immobilization is confirmed by surface characterization. Surfaces functionalized with alginate lyase exhibit anti-adhesive properties, inhibiting the attachment of the mucoid strain. Moreover, surfaces modified with this enzyme also inhibit the adhesion of the tested non-mucoid strain. Unexpectedly, treatment with heat-inactivated enzyme also inhibits the attachment of mucoid and non-mucoid P. aeruginosa strains. These findings suggest that the antibacterial performance of alginate lyase functional coatings is catalysis-independent, highlighting the importance of further studies to better understand its mechanism of action against P. aeruginosa strains.

  8. Polygalacturonase production by calcium alginate immobilized Enterobacter aerogenes NBO2 cells.

    PubMed

    Darah, I; Nisha, M; Lim, Sheh-Hong

    2015-03-01

    Bacterial cells of Enterobacter aerogenes NBO2 were entrapped in calcium alginate beads in order to enhance polygalacturonase production compared to free cells. The optimized condition of 5 % (w/v) sodium alginate concentration, agitation speed of 250 rpm, and 15 beads of calcium alginate with inoculum size of 4 % (v/v; 5.4 × 10(7) cells/ml) produced 23.48 U/mL of polygalacturonase compared to free cells of 18.54 U/ml. There was about 26.6 % increment in polygalaturonase production. However, in this study, there was 296.6 % of increment in polygalacturonase production after improvement parameters compared to before improvement parameters of calcium alginate bead immobilization cells (5.92 U/ml). This research has indicated that optimized physical parameters of calcium alginate bead immobilization cells have significantly enhanced the production of polygalacturonase.

  9. Swelling and mechanical properties of alginate hydrogels with respect to promotion of neural growth.

    PubMed

    Matyash, Marina; Despang, Florian; Ikonomidou, Chrysanthy; Gelinsky, Michael

    2014-05-01

    Soft alginate hydrogels support robust neurite outgrowth, but their rapid disintegration in solutions of high ionic strength restricts them from long-term in vivo applications. Aiming to enhance the mechanical stability of soft alginate hydrogels, we investigated how changes in pH and ionic strength during gelation influence the swelling, stiffness, and disintegration of a three-dimensional (3D) alginate matrix and its ability to support neurite outgrowth. Hydrogels were generated from dry alginate layers through ionic crosslinks with Ca(2+) (≤ 10 mM) in solutions of low or high ionic strength and at pH 5.5 or 7.4. High- and low-viscosity alginates with different molecular compositions demonstrated pH and ionic strength-independent increases in hydrogel volume with decreases in Ca(2+) concentrations from 10 to 2 mM. Only soft hydrogels that were synthesized in the presence of 150 mM of NaCl (Ca-alginate NaCl) displayed long-term volume stability in buffered physiological saline, whereas analogous hydrogels generated in NaCl-free conditions (Ca-alginate) collapsed. The stiffnesses of Ca-alginate NaCl hydrogels elevated from 0.01 to 19 kPa as the Ca(2+)-concentration was raised from 2 to 10 mM; however, only Ca-alginate NaCl hydrogels with an elastic modulus ≤ 1.5 kPa that were generated with ≤ 4 mM of Ca(2+) supported robust neurite outgrowth in primary neuronal cultures. In conclusion, soft Ca-alginate NaCl hydrogels combine mechanical stability in solutions of high ionic strength with the ability to support neural growth and could be useful as 3D implants for neural regeneration in vivo.

  10. Design of controlled-release solid dosage forms of alginate and chitosan using microwave.

    PubMed

    Wong, Tin Wui; Chan, Lai Wah; Kho, Shyan Bin; Sia Heng, Paul Wan

    2002-12-05

    The influence of microwave irradiation on the drug release properties of alginate, alginate-chitosan and chitosan beads was investigated. The beads were prepared with the highest possible concentration of polymer by an extrusion method. Sulphathiazole was selected as a model drug. The beads were subjected to microwave irradiation at various combinations of irradiation power and time. The profiles of drug dissolution, drug content, drug stability, drug polymorphism, drug-polymer interaction, polymer crosslinkage and complexation were determined by dissolution testing, drug content assay, differential scanning calorimetry (DSC) and fourier transform infra-red spectroscopy (FTIR). The chemical stability of the drug entrapped in the beads was unaffected by the microwave irradiation. However, the drug in the chitosan beads underwent polymorphic changes. Polymorphic changes were prevented by means of drug-alginate interaction in alginate and alginate-chitosan beads. Changes in the polymorphic state of drug were found to have insignificant effect on the drug release profiles of chitosan beads. The release-retarding property of alginate and alginate-chitosan beads was significantly enhanced by subjecting the beads to microwave irradiation. Positively charged calcium ions and chitosan are known to interact with negatively charged alginate. DSC and FTIR analyses indicated that the reduction in rate and extent of drug released from the treated beads was primarily due to additional formation of non-ionic bonds, involving alginate crosslinkage and alginate-chitosan complexation. The results showed that microwave technology can be employed in the design of solid dosage forms for controlled-release application without the use of noxious chemical agents.

  11. A conformational landscape for alginate secretion across the outer membrane of Pseudomonas aeruginosa

    SciTech Connect

    Tan, Jingquan; Rouse, Sarah L.; Li, Dianfan; Pye, Valerie E.; Vogeley, Lutz; Brinth, Alette R.; El Arnaout, Toufic; Whitney, John C.; Howell, P. Lynne; Sansom, Mark S. P.; Caffrey, Martin

    2014-08-01

    Crystal structures of the β-barrel porin AlgE reveal a mechanism whereby alginate is exported from P. aeruginosa for biofilm formation. The exopolysaccharide alginate is an important component of biofilms produced by Pseudomonas aeruginosa, a major pathogen that contributes to the demise of cystic fibrosis patients. Alginate exits the cell via the outer membrane porin AlgE. X-ray structures of several AlgE crystal forms are reported here. Whilst all share a common β-barrel constitution, they differ in the degree to which loops L2 and T8 are ordered. L2 and T8 have been identified as an extracellular gate (E-gate) and a periplasmic gate (P-gate), respectively, that reside on either side of an alginate-selectivity pore located midway through AlgE. Passage of alginate across the membrane is proposed to be regulated by the sequential opening and closing of the two gates. In one crystal form, the selectivity pore contains a bound citrate. Because citrate mimics the uronate monomers of alginate, its location is taken to highlight a route through AlgE taken by alginate as it crosses the pore. Docking and molecular-dynamics simulations support and extend the proposed transport mechanism. Specifically, the P-gate and E-gate are flexible and move between open and closed states. Citrate can leave the selectivity pore bidirectionally. Alginate docks stably in a linear conformation through the open pore. To translate across the pore, a force is required that presumably is provided by the alginate-synthesis machinery. Accessing the open pore is facilitated by complex formation between AlgE and the periplasmic protein AlgK. Alginate can thread through a continuous pore in the complex, suggesting that AlgK pre-orients newly synthesized exopolysaccharide for delivery to AlgE.

  12. Physico-chemical properties of alginate/shellac aqueous-core capsules: Influence of membrane architecture on riboflavin release.

    PubMed

    Ben Messaoud, Ghazi; Sánchez-González, Laura; Probst, Laurent; Jeandel, Carole; Arab-Tehrany, Elmira; Desobry, Stéphane

    2016-06-25

    To enhance physico-chemical properties of alginate liquid-core capsules, shellac was incorporated into the membrane (composite capsules) or as an additional external layer (coated capsules). The influence of pH, coating time, shellac concentration and preparation mechanism (acid or calcium precipitation) were investigated. Results showed that shellac significantly influenced the capsules properties. The feasibility of shellac incorporation was closely related to the preparation conditions as confirmed by Infrared spectroscopy. Optical, fluorescence and scanning electron microscopy, highlighted different capsules and membranes architectures. In contrast to simple and composite capsules, coated capsules showed a pH-dependent release of the entrapped vitamin especially after shellac crosslinking with calcium. Heating of coated capsules above the glass transition temperature investigated by Differential Scanning Calorimetry, led to irreversible structural change due to thermoplastic behavior of shellac and enhanced riboflavin retention under acidic conditions. This global approach is useful to control release mechanism of low molecular weight molecules from macro and micro-capsules.

  13. Synthesis of "click" alginate hydrogel capsules and comparison of their stability, water swelling, and diffusion properties with that of Ca(+2) crosslinked alginate capsules.

    PubMed

    Breger, Joyce C; Fisher, Benjamin; Samy, Raghu; Pollack, Steven; Wang, Nam Sun; Isayeva, Irada

    2015-07-01

    Ionically crosslinked alginate hydrogels have been extensively explored for encapsulation and immunoisolation of living cells/tissues to develop implantable cell therapies, such as islet encapsulation for bioartificial pancreas. Chemical instability of these hydrogels during long-term implantation hinders the development of viable cell therapy. The exchange between divalent crosslinking ions (e.g., Ca(+2) ) with monovalent ions from physiological environment causes alginate hydrogels to degrade, resulting in exposure of the donor tissue to the host's immune system and graft failure. The goal of this study was to improve stability of alginate hydrogels by utilizing covalent "click" crosslinking while preserving other biomedically viable hydrogel properties. Alginate was first functionalized to contain either pendant alkyne or azide functionalities, and subsequently reacted via "click" chemistry to form "click" gel capsules. Alginate functionalization was confirmed by NMR and gel permeation chromatography. When compared with Ca(+2) capsules, "click" capsules exhibited superior stability in ionic media, while showing higher permeability to small size diffusants and similar molecular weight cut-off and water swelling. Physicochemical properties of "click" alginate hydrogels demonstrate their potential utility for therapeutic cell encapsulation and other biomedical applications.

  14. Effect of sodium alginate coating enriched with horsemint (Mentha longifolia) essential oil on the quality of bighead carp fillets during storage at 4°C

    PubMed Central

    Heydari, Ramin; Bavandi, Shahmir; Javadian, Seyed Roholla

    2015-01-01

    Effect of sodium alginate coating enriched with horsemint essential oil (HEO) on the quality of bighead carp (Aristichthys nobilis) fillets at refrigeration temperature (4 ± 1°C) was studied. Bighead carp fillets were coated with neat sodium alginate (SA) and sodium alginate containing 0.5 and 1% v/v of HEO and their quality changes in terms of total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), and microbial counts were investigated. SA coating enriched with the essential oil could reduce the spoilage of the fillets and extend their shelf-life. Samples treated with SA-containing HEO showed significantly (P < 0.05) lower TVB-N content and lipid oxidation, as reflected by lower PV, FFA and TBA values during the storage period compared with the SA and control. The treatment also reduced the degree of microbial deterioration of the fillets (about 1.5 log10 CFU/g) more efficiently than the SA. PMID:25987993

  15. Graft copolymer based on (sodium alginate-g-acrylamide): Characterization and study of Water swelling capacity, metal ion sorption, flocculation and resistance to biodegradability.

    PubMed

    Sand, Arpit; Vyas, Aparna; Gupta, A K

    2016-09-01

    Graft copolymer of alginate and acrylamide was synthesized by grafting acrylamide chains on to alginate by free radical polymerization using potassium bromate/thiourea redox system in an inert atmosphere. The reaction conditions for maximum grafting have been optimized by varying the reaction variables, including the concentration of acrylamide (3.0×10(2)-9.3×10(2)moldm(-3)), potassium bromate (8×10(-3)-16×10(-3)moldm(-3)), thiourea (1.6×10(-3)-4.8×10(-3)moldm(-3)), sulphuric acid (3.0×10(-3)-7×10(-3)moldm(-3)), alginate (0.6-1.6gdm(-3)) along with time duration (60-180min) and temperature (30-50°C). Water swelling capacity, metal ion sorption, flocculation and resistance to biodegradability studies of synthesized graft copolymer have been performed with respect to the parent polymer. The grafted polymers were characterized by FTIR spectroscopy and thermo gravimetric analysis.

  16. Effect of sodium alginate coating incorporated with nisin, Cinnamomum zeylanicum, and rosemary essential oils on microbial quality of chicken meat and fate of Listeria monocytogenes during refrigeration.

    PubMed

    Raeisi, Mojtaba; Tabaraei, Alijan; Hashemi, Mohammad; Behnampour, Nasser

    2016-12-05

    The present study was conducted to preserve the microbial quality of chicken meat fillets during storage time by using sodium alginate active coating solutions incorporated with different natural antimicrobials including nisin, Cinnamomum zeylanicum (cinnamon), and rosemary essential oils (EOs) which were added individually and in combination. The samples were stored in refrigeration condition for 15days and were analyzed for total viable count, Enterobacteriaceae count, lactic acid bacteria count, Pseudomonas spp. count, psychrotrophic count, and yeast and mold count, as well as fate of inoculated Listeria monocytogenes at 3-day intervals. Results indicated that values of tested microbial indicators in all samples increased during storage. Antimicrobial agents, when used in combination, had stronger effect in preserving the microbial quality of chicken meat samples rather than their individual use and the strongest effect was observed in samples coated with alginate solution containing both cinnamon and rosemary EOs (CEO+REO). However, all treatments significantly inhibited microbial growth when compared to the control (P<0.05). Therefore, based on the results of this study, application of alginate coating solutions containing nisin, cinnamon, and rosemary EOs as natural preservatives is recommended in meat products especially in chicken meats.

  17. Sustained release of verapamil hydrochloride from sodium alginate microcapsules.

    PubMed

    Farhana, S Ayesha; Shantakumar, S M; Shyale, Somashekar; Shalam, Md; Narasu, Laxmi

    2010-04-01

    The objective of the present study was to develop sustained release microcapsules of verapamil hydrochloride (VH) using biodegradable polymers. For this purpose microcapsules embedded verapamil hydrochloride were prepared using sodium alginate alone and also by incorporating some co polymers like methyl cellulose (MC), sodium carboxy methyl cellulose (SCMC) , poly vinyl pyrollidone (PVP) and xanthan gum by employing complex emulsion method of microencapsulation. Microcapsules were prepared in various core: coat ratios to know the effect of polymer and co polymers on drug release. Overall ten formulations were prepared and evaluated for flow behaviour, sieve analysis, drug entrapment efficiency, in vitro dissolution studies, stability studies, including scanning electron microscopy and DSC. The resulting microcapsules were discrete, large, spherical and also free flowing. The drug content in all the batches of microcapsules was found to be uniform. The release was depended on core: coat ratio and nature of the polymers. FTIR analysis revealed chemical integrity between Verapamil hydrochloride (VH), sodium alginate and between the copolymers. Among the four copolymers used methyl cellulose retarded the drug release more than the other three, hence the same formulation was subjected for in vivo studies. The drug release from the microcapsules was found to be following non fickian diffusion. Mechanism of drug release was diffusion controlled first order kinetics. Drug diffusion co efficient and correlation co efficient were also assessed by using various mathematical models. In vivo result analysis of pharmacokinetic parameters revealed that t max of reference and test formulations were almost same. From the study it was concluded that, sustained release Verapamil hydro chloride microcapsules could be achieved with success using sodium alginate alone and also in combination with other biodegradable polymers.

  18. Evaluation of the diffusion coefficient for controlled release of oxytetracycline from alginate/chitosan/poly(ethylene glycol) microbeads in simulated gastrointestinal environments.

    PubMed

    Cruz, Maria C Pinto; Ravagnani, Sergio P; Brogna, Fabio M S; Campana, Sérgio P; Triviño, Galo Cardenas; Lisboa, Antonio C Luz; Mei, Lucia H Innocentini

    2004-12-01

    Diffusion studies of OTC (oxytetracycline) entrapped in microbeads of calcium alginate, calcium alginate coacervated with chitosan (of high, medium and low viscosity) and calcium alginate coacervated with chitosan of low viscosity, covered with PEG [poly(ethylene glycol) of molecular mass 2, 4.6 and 10 kDa, were carried out at 37+/-0.5 degrees C, in pH 7.4 and pH 1.2 buffer solutions - conditions similar to those found in the gastrointestinal system. The diffusion coefficient, or diffusivity (D), of OTC was calculated by equations provided by Crank [(1975) Mathematics in Diffusion, p. 85, Clarendon Press, Oxford] for diffusion, which follows Fick's [(1855) Ann. Physik (Leipzig) 170, 59] second law, considering the diffusion from the inner parts to the surface of the microbeads. The least-squares and the Newton-Raphson [Carnahan, Luther and Wilkes (1969) Applied Numerical Methods, p. 319, John Wiley & Sons, New York] methods were used to obtain the diffusion coefficients. The microbead swelling at pH 7.4 and OTC diffusion is classically Fickian, suggesting that the OTC transport, in this case, is controlled by the exchange rates of free water and relaxation of calcium alginate chains. In case of acid media, it was observed that the phenomenon did not follow Fick's law, owing, probably, to the high solubility of the OTC in this environment. It was possible to modulate the release rate of OTC in several types of microbeads. The presence of cracks formed during the process of drying the microbeads was observed by scanning electron microscopy.

  19. AAS 228: Day 4

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-06-01

    Editors Note: Lastweek we were at the 228th AAS Meeting in San Diego, CA. Here is a final post aboutselectedevents on the last day of the meeting, written by authors fromastrobites.com, a grad-student collaborative project with which we recently announced a new partnership! Starting in July,keep an eye out for astrobites postsat AAS Nova in between Highlights(i.e., on Tuesdays and Thursdays).Were excited to be working together to bring you more recent astronomy research from AAS journals!Extrasolar Planets: Detection (by Leonardo dos Santos)Thursdays first session on exoplanets was about detecting these distant worlds, and the opening talk was given by Robert Siverd (Las Cumbres Observatory). He describes the NRES, a network of spectrographs that will look for exoplanets using the radial velocity method. One of the coolest aspects of this instrument is that it will feature an on the fly scheduling system that will perform observations as efficiently as possible. The spectrograph is still being tested, but a unit will be deployed at CTIO later this year.@lcogt contracted by @NASA_TESS for follow up of their candidates. #aas228 Jessie Christiansen (@aussiastronomer) June 16, 2016Measuring the depths of transits and eclipses in Spitzer has been problematic in the past, since the Spitzer instrument IRAC (InfraRed Array Camera) has a non-uniform response in its detectors pixels. But, as reported by James Ingalls (Spitzer Science Center, Caltech), observers are circumventing this issue by using what they call the staring mode (avoiding large pointing jumps) and an algorithm to pick sweet spot pixels. Moreover, the results from the IRAC Data Challenge are helping to better understand its behavior. Giuseppe Morello (University College London), on the other hand, explained how his research group gets rid of instrumental effects from IRAC using machine learning. This method removes systematics from exoplanet transit data no matter if the noise source is from an instrument or

  20. Encapsulation of ammonium molybdophosphate and zirconium phosphate in alginate matrix for the sorption of rubidium(I).

    PubMed

    Krys, Pawel; Testa, Flaviano; Trochimczuk, Andrzej; Pin, Christian; Taulemesse, Jean-Marie; Vincent, Thierry; Guibal, Eric

    2013-11-01

    Ammonium molybdophosphate and Phozir (alone or in combination) have been encapsulated in alginate beads for the synthesis of rubidium sorbents. SEM and SEM-EDX analyses confirm the homogeneity of the sorbents in terms of composition and metal binding. AMP sorbent is less sensitive to pH than Phozir, and optimum pH is close to pH 3 for the binding of Rb(I). The Langmuir equation fitted well sorption isotherms and the maximum sorption capacities were in the range 0.65-0.74 mmol Rb g(-1). The resistance to intraparticle diffusion contributes to control uptake kinetics (effect of particle size) though the presence of solid inorganic particles reduces the impact of drying alginate capsules (preventing the collapse of the porous structure during the drying step). Breakthrough curves demonstrate the potential of these sorbents for the dynamic sorption of Rb(I) while using ammonium chloride (combined to nitric acid) allows recovering Rb(I) from loaded sorbents.

  1. Characterization of smart auto-degradative hydrogel matrix containing alginate lyase to enhance levofloxacin delivery against bacterial biofilms.

    PubMed

    Islan, German A; Dini, Cecilia; Bartel, Laura C; Bolzán, Alejandro D; Castro, Guillermo R

    2015-12-30

    The aim of the present work is the characterization of smart auto-degradable microspheres composed of calcium alginate/high methoxylated pectin containing an alginate lyase (AL) from Sphingobacterium multivorum and levofloxacin. Microspheres were prepared by ionotropic gelation containing AL in its inactive form at pH 4.0. Incubation of microspheres in Tris-HCl and PBS buffers at pH 7.40 allowed to establish the effect of ion-chelating phosphate on matrix erodability and suggested an intrinsically activation of AL by turning the pH close to neutrality. Scanning electron and optical microscopies revealed the presence of holes and surface changes in AL containing microspheres. Furthermore, texturometric parameters, DSC profiles and swelling properties were showing strong changes in microspheres properties. Encapsulation of levofloxacin into microspheres containing AL showed 70% efficiency and 35% enhancement of antimicrobial activity against Pseudomonas aeruginosa biofilm. Levofloxacin release from microspheres was not changed at acidic pH, but was modified at neutral pH in presence of AL. Advantageously, only gel matrix debris were detectable after overnight incubation, indicating an autodegradative gel process activated by the pH. Absence of matrix cytotoxicity and a reduction of the levofloxacin toxicity after encapsulation were observed in mammalian CHO-K1 cell cultures. These properties make the system a potent and versatile tool for antibiotic oral delivery targeted to intestine, enhancing the drug bioavailability to eradicate bacterial biofilm and avoiding possible intestinal obstructions.

  2. Proteomic Analysis of the Increased Stress Tolerance of Saccharomyces cerevisiae Encapsulated in Liquid Core Alginate-Chitosan Capsules

    PubMed Central

    Westman, Johan O.; Taherzadeh, Mohammad J.; Franzén, Carl Johan

    2012-01-01

    Saccharomyces cerevisiae CBS8066 encapsulated in semi-permeable alginate or alginate-chitosan liquid core capsules have been shown to have an enhanced tolerance towards complex dilute-acid lignocellulose hydrolysates and the lignocellulose-derived inhibitor furfural, as well as towards high temperatures. The underlying molecular reasons for these effects have however not been elucidated. In this study we have investigated the response of the encapsulation on the proteome level in the yeast cells, in comparison with cells grown freely in suspension under otherwise similar conditions. The proteomic analysis was performed on whole cell protein extracts using nLC-MS/MS with TMT® labelling and 2-D DIGE. 842 and 52 proteins were identified using each method, respectively. The abundances of 213 proteins were significantly different between encapsulated and suspended cells, with good correlation between the fold change ratios obtained by the two methods for proteins identified in both. Encapsulation of the yeast caused an up-regulation of glucose-repressed proteins and of both general and starvation-specific stress responses, such as the trehalose biosynthesis pathway, and down-regulation of proteins linked to growth and protein synthesis. The encapsulation leads to a lack of nutrients for cells close to the core of the capsule due to mass transfer limitations. The triggering of the stress response may be beneficial for the cells in certain conditions, for example leading to the increased tolerance towards high temperatures and certain inhibitors. PMID:23152898

  3. Gelation time, homogeneity, and rupture testing of alginate-calcium carbonate-hydrogen peroxide gels for use as wound dressings.

    PubMed

    Alexander, Brendan R; Murphy, Kathleen E; Gallagher, Joanne; Farrell, Garrett F; Taggart, Gertie

    2012-02-01

    The care of chronic wounds carries a heavy financial burden on the healthcare industry, with billons being spent annually on their treatment. This, coupled with a decreased quality of life for sufferers, has led to a real urgency in developing inexpensive wound dressings that promote wound healing. Alginate gels for application as wound dressings were formed by varying alginate (0%-6% w/v), calcium carbonate (0%-1% w/v), hydrogen peroxide (0%-3.75% v/v), and hyaluronic acid (0-1.25 mg/L) content. The aging effects on the physical properties of the gels over a 14-day period were also investigated. The results indicated that the concentration of calcium carbonate and hydrogen peroxide, as well as sample age, all had a significant effect on the rupture characteristics and gelation time of the gels. Increased calcium carbonate content caused an increase in rupture force and rupture energy values, whereas increased hydrogen peroxide content and sample age resulted in a decrease in rupture force and rupture energy measurements. Increased calcium carbonate and hydrogen peroxide content produced a decrease in the time required for gel formation. Statistical models were also produced to provide a means of estimating rupture characteristics and gelation times for gels containing other concentrations of these components.

  4. Anticoagulant and FGF/FGFR