sodium-hypochlorite and sodium-bromide

A xanthouronic acid sodium salt called xanthouronan was produced from xanthan by regioselective oxidation with NaOCl/NaBr using 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) as catalyst. The efficiency of the one pot TEMPO-mediated oxidation was confirmed by HPAEC-PAD, (13)C NMR, and FT-IR. The oxidation degree was close to 98% and the mass yield of this new polyglucuronic acid was higher than 90% (w/w). The macromolecular characterization of xanthouronan using SEC-MALLS showed a molecular size reduced by a third due to the oxidation treatment and the degree of polymerization (DP) of the xanthouronan form was about 665. The evaluation of the enzymatic degradation of this C-6 carboxylated xanthan by various polysaccharide hydrolases and one polysaccharide lyase showed its high resistant to biodegradation. The antioxidant activity of xanthouronan was also tested by using the 2,2'-diphenyl-1-picrylhydrazyle (DPPH) and hydroxyl radical procedures. At 1 g/L, xanthouronan presented 75% of the ascorbic acid antioxidant activity.

Topics: Antioxidants; Biphenyl Compounds; Bromides; Catalysis; Cyclic N-Oxides; Oxidation-Reduction; Picrates; Polysaccharides; Polysaccharides, Bacterial; Sodium Compounds; Sodium Hydroxide; Sodium Hypochlorite; Uronic Acids

One-sided surface oxidation of lyocell type cellulose fabric can be achieved by use of a modified TEMPO-mediated oxidation system. A borate-based buffer was used to maintain stable pH conditions and screen printing was applied to achieve oxidation on the fabric surface only. To formulate an applicable procedure, the TEMPO/NaBr/NaOCl system was split into two treatment steps: firstly, the fabric was impregnated with a buffered TEMPO/NaBr solution and dried, then a thickened NaOCl paste was printed on the fabric. FTIR-ATR spectra and methylene blue sorption experiments demonstrated successful modification on the printed side of the fabric. Substantial increases in carboxylic group content and water retention value were observed. The higher concentration of carboxylic groups on the fabric surface also led to a localised increase in binding capacity for Ca(2+)-ions. This new concept permits controlled oxidation of cellulose surfaces by printing techniques.

Topics: Bromides; Cellulose; Cotton Fiber; Cyclic N-Oxides; Oxidants; Oxidation-Reduction; Printing; Sodium Compounds; Sodium Hypochlorite; Spectrophotometry, Atomic; Spectroscopy, Fourier Transform Infrared; Surface Properties; Textiles

Native hyaluronan (HA) has been oxidized to polyaldehyde polymers with a degree of substitution (DS) of up to 50%. Two different procedures enabling the control of the degree of substitution were followed in this study. Selective oxidation of primary hydroxyl groups of N-acetyl-D-glucosamine of hyaluronan was performed either in an aqueous solution containing AcNH-TEMPO/NaBr/NaOCl or in an aprotic solvent containing Dess-Martin periodinane (DMP). It was found that a change of reaction parameters (reaction time and temperature, type of catalyst, oxidant-to-HA ratio, presence of nitrogen, buffer type, and concentration) had an influence on the degree of substitution and molecular weight. The derivatives were characterized by MS, NMR spectroscopy, and SEC-MALLS. Degradation of hyaluronic acid by the oxidant was observed and confirmed by SEC. The effect of oxidized derivatives of hyaluronan on cells was studied by means of NIH 3T3 fibroblast viability, which indicates that prepared hyaluronan polyaldehydes are biocompatible and suitable for medical applications and tissue engineering. The function of polyaldehyde as precursor for other modification was illustrated in the reaction with lysine.

Topics: Acetylglucosamine; Aldehydes; Animals; Biocompatible Materials; Biopolymers; Bromides; Catalysis; Cell Survival; Cyclic N-Oxides; Hyaluronic Acid; Imino Pyranoses; Magnetic Resonance Spectroscopy; Mice; Molecular Weight; NIH 3T3 Cells; Nitrogen; Oxidation-Reduction; Sodium Compounds; Sodium Hypochlorite; Temperature

A number of studies have shown that the production of chemical defences is costly in terrestrial vascular plants. However, these studies do not necessarily reflect the costs of defence production in macroalgae, due to structural and functional differences between vascular plants and macroalgae. Using a specific culturing technique, we experimentally manipulated the defence production in the red alga Bonnemaisonia hamifera to examine if the defence is costly in terms of growth. Furthermore, we tested if the defence provides fitness benefits by reducing harmful bacterial colonisation of the alga. Costly defences should provide benefits to the producer in order to be maintained in natural populations, but such benefits through protection against harmful bacterial colonisation have rarely been documented in macroalgae. We found that algae with experimentally impaired defence production, but with an externally controlled epibacterial load, grew significantly better than algae with normal defence production. We also found that undefended algae exposed to a natural epibacterial load experienced a substantial reduction in growth and a 6-fold increase in cell bleaching, compared to controls. Thus, this study provides experimental evidence that chemical defence production in macroalgae is costly, but that the cost is outweighed by fitness benefits provided through protection against harmful bacterial colonisation.

Topics: Anti-Bacterial Agents; Bacteria; Bacterial Load; Biological Evolution; Bromides; Ketones; Rhodophyta; Sodium Compounds; Sodium Hypochlorite

TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated 6-carboxy β-chitin derivatives (T-chitin) with different carboxylate content were successfully synthesized by controlling the addition level of NaClO as the primary oxidant. The structural and biochemical properties of the derivatives were investigated. The carboxylate contents of the derivatives calculated by electrical conductivity titration were 1.33, 1.68, 1.80, and 2.08 mmol/g, respectively. The yield of T-chitin with carboxylate content of 2.08 mmol/g reached 74.55%. T-chitin exhibited stronger bile acid binding capacities than that of β-chitin. The scavenging ability of T-chitin against hydroxyl radicals improved with increasing concentration, and EC(50) values were below 1.2 mg/mL. All T-chitin exhibited a strong ferrous ion chelating effect. At 8 mg/mL, the chelating effects of T-chitin with carboxylate content of 0.81 mmol/g reached 80.15%. These results showed that T-chitin had good bile acid binding capacity and antioxidant activities and it may be a potential antioxidant in vitro.

Topics: Animal Shells; Animals; Bile Acids and Salts; Biphenyl Compounds; Bromides; Carboxylic Acids; Chitin; Cyclic N-Oxides; Decapodiformes; Free Radical Scavengers; Hydroxyl Radical; Iron Chelating Agents; Oxidation-Reduction; Picrates; Sodium Compounds; Sodium Hypochlorite

Cellulose nanowhiskers as a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Herein, for the first time, a novel controllable fabrication of spider-web-like nanoporous networks based on jute cellulose nanowhiskers (JCNs) deposited on the electrospun (ES) nanofibrous membrane by simple directly immersion-drying method is reported. Jute cellulose nanowhiskers were extracted from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization. The morphology of JCNs nanoporous networks/ES nanofibrous membrane architecture, including coverage rate, pore-width and layer-by-layer packing structure of the nanoporous networks, can be finely controlled by regulating the JCNs dispersions properties and drying conditions. The versatile nanoporous network composites based on jute cellulose nanowhiskers with ultrathin diameters (3-10 nm) and nanofibrous membrane supports with diameters of 100-300 nm, would be particularly useful for filter applications.

Topics: Animals; Biomimetics; Bromides; Cellulose; Cyclic N-Oxides; Mechanical Phenomena; Membranes, Artificial; Nanostructures; Oxidation-Reduction; Porosity; Quaternary Ammonium Compounds; Sodium Compounds; Sodium Hypochlorite; Spiders; Surface Tension; Vegetables

Although sodium hypochlorite is routinely used as an irrigant, the scope and limitation of another hypohalide sodium hypobromite has not been adequately studied. The objective of this study was to compare the cytotoxic effects of sodium hypobromite and sodium hypochlorite on human osteoblasts by evaluating cell proliferation. One day after plating and every other day after that, cells were treated with a combination of sodium hypochlorite and sodium bromide, resulting into three molar ratios of activated sodium hypobromite. Positive control cells were not treated with hypohalides, while negative controls were separately treated with hypochlorite or bromide alone. Photomicrographic analysis of the cultures was done on days 1 and 6 of treatment. Trypsinized cells were counted to determine cell proliferation. Our results show that sodium bromide is more cytotoxic compared to sodium hypochlorite or activated sodium hypobromite. In activated sodium hypobromite, 4:1 molar ratio was less cytotoxic compared to other molar ratios.

Topics: Analysis of Variance; Bromates; Bromides; Cell Proliferation; Cells, Cultured; Fetus; Humans; Osteoblasts; Root Canal Irrigants; Sodium Compounds; Sodium Hypochlorite; Statistics, Nonparametric

Chitosan was selectively oxidized at C-6 primary alcohol groups by TEMPO in the presence of sodium hypochlorite (NaOCl) and sodium bromide (NaBr), and also non-specifically oxidized only by NaOCl. Sequentially oxidized chitosan samples from 25 to 100% were produced by 25% increment, from both oxidation processes. By introducing carbonyl groups in chitosan structure with either oxidizing process, the water solubility was shown to be enhancing from all the oxidized sample groups. At the 25% of non-specific oxidation, 0.56% of solubility was detected but there was no proportional increase in solubility as the oxidation level increased. Moreover, the decreases in solubility were observed at 50%-oxidized (0.43%) and 100%-oxidized (0.45%) chitosan samples. During the specific oxidation process, 25%-oxidized 6-oxychitosan had the highest solubility, and the solubility decreased substantially from 0.72 to 0.15% as the degree of oxidation increased from 25 to 100%. Possibly, excessive incorporation of negative charges on chitosan resulted in the aggregation among 6-oxychitosan molecules by charge-charge interactions. The strongest cholic acid-retardation index (CRI, %) of highly soluble 25%-oxidized 6-oxychitosan was consistently observed until 24h of dialysis, which means the CRI is closely related to the water solubility of 6-oxychitosan. Therefore, the solubility improvement should be considered for enhancing the biological activity such as bile acid-binding capacity. Also, it was suggested that negative charge increase in chitosan structure above a certain level led to adverse effect on the binding capacity.

Topics: Alcohols; Bile Acids and Salts; Biocompatible Materials; Bromides; Chitosan; Cholic Acid; Cyclic N-Oxides; Dose-Response Relationship, Drug; Hydrogen-Ion Concentration; Macromolecular Substances; Oxygen; Polymers; Sodium Compounds; Sodium Hypochlorite; Solubility; Temperature; Water

Oxidation of sucrose by the NaOCl/TEMPO system provided sucrose tricarboxylate without the addition of sodium bromide as co-catalyst when high-frequency (500 kHz) ultrasound was applied, in contrast to very limited conversion without sonication. In the presence of sodium bromide, sonication also caused acceleration of the oxidation. The rate increase due to sonication of the oxidant system prior to sucrose addition suggests that ultrasound acts at the level of the formation of the nitrosonium ion, the active oxidising species in the catalytic cycle.

Topics: Antioxidants; Bromides; Catalysis; Cyclic N-Oxides; Molecular Structure; Oxidation-Reduction; Sodium Compounds; Sodium Hypochlorite; Sucrose; Tricarboxylic Acids; Ultrasonics