Presence Of Carboxymethyl Cellulose Research Articles

Efeitos da injeção intraorbitária de carboximetilcelulose 6,0% em coelhos: análise histológica e da mecânica ocular

To determine the effects of 6.0% carboxymethylcellulose (CMC) in modifying the oculomotor system of rabbits by means of viscoelastic action forces, the durability of this effect and possible inflammatory reaction. Twenty-five New Zealand rabbits were divided into two experimental groups: one treated with a peribulbar injection of 6.0% CMC and a control group submitted to peribulbar injection of 3.0 cc of physiological saline. The group submitted to peribulbar CMC injection was divided into four subgroups respectively receiving the following volumes: 1.0, 1.5, 2.0 and 3.0 cc. The force needed to promote tangential adduction dislocations, external ophthalmologic signs and intraocular pressure were evaluated. The animals were sacrificed on the 60th day after the injection for histological analysis. The mean force detected 60 days after the injection of 6.0% CMC was lower in the 1.0 treated subgroup and higher in the 1.5, 2.0 and 3.0 treated subgroups relative to the force before injection. Histological analysis revealed histiocytic infiltration with fibrosis in the subgroups in which there was an increase in force and the presence of CMC in periocular tissues. 6.0% CMC acted as a modifier of the oculomotor system of rabbits, facilitating or impairing movements. It was not possible to conclude whether the increase in force occurred as a consequence of the inflammatory process alone or of the sum of inflammation and a possible viscous attrition provoked by CMC.

Formulation and coating of microneedles with inactivated influenza virus to improve vaccine stability and immunogenicity

Microneedle patches coated with solid-state influenza vaccine have been developed to improve vaccine efficacy and patient coverage. However, dip coating microneedles with influenza vaccine can reduce antigen activity. In this study, we sought to determine the experimental factors and mechanistic pathways by which inactivated influenza vaccine can lose activity, as well as develop and assess improved microneedle coating formulations that protect the antigen from activity loss. After coating microneedles using a standard vaccine formulation, the stability of influenza vaccine was reduced to just 2%, as measured by hemagglutination activity. The presence of carboxymethylcellulose, which was added to increase viscosity of the coating formulation, was shown to contribute to vaccine activity loss. After screening a panel of candidate stabilizers, the addition of trehalose to the coating formulation was found to protect the antigen and retain 48–82% antigen activity for all three major strains of seasonal influenza: H1N1, H3N2 and B. Influenza vaccine coated in this way also exhibited thermal stability, such that activity loss was independent of temperature over the range of 4–37 °C for 24 h. Dynamic light scattering measurements showed that antigen activity loss was associated with virus particle aggregation, and that stabilization using trehalose largely blocked this aggregation. Finally, microneedles using an optimized vaccine coating formulation were applied to the skin to vaccinate mice. Microneedle vaccination induced robust systemic and functional antibodies and provided complete protection against lethal challenge infection similar to conventional intramuscular injection. Overall, these results show that antigen activity loss during microneedle coating can be largely prevented through optimized formulation and that stabilized microneedle patches can be used for effective vaccination.

Nanocomposites of bacterial cellulose/hydroxyapatite for biomedical applications

In the present work, a nanocomposite material formed by bacterial cellulose (BC) networks and calcium-deficient hydroxyapatite (HAp) powders was synthesized and characterized. The HAp nanoparticles were previously prepared by a wet chemical precipitation method, starting from aqueous solutions of calcium nitrate and di-ammonium phosphate salts. Energy-dispersive spectroscopy reveals that the prepared HAp corresponds to calcium-deficient hydroxyapatite. BC-HAp nanocomposites were prepared by introducing carboxymethylcellulose (CMC) into the bacteria culture media. HAp nanoparticles were then introduced and remained suspended in the culture medium during the formation of cellulose nanofibrils. The maximum gel thickness was obtained after 21 days of bacteria cultivation. X-ray diffractograms showed the difference of crystallinity among the materials involved in the formation of nanocomposites. The inorganic and organic bonds that corresponded to hydroxyapatite and bacterial cellulose respectively, were depicted by attenuated total reflectance Fourier transform infrared spectra. Scanning electron microscopy and atomic force microscopy measurements confirmed the formation of networks and fibres with smaller diameter corresponding to BC synthesized in the presence of CMC. Image analysis was also used to assess the orientation distributions and Feret diameters for networks of BC and BC-CMC. Thermogravimetric analysis showed that the amount of the mineral phase is 23.7% of the total weight of the nanocomposite. Moreover, HEK cells were cultivated and the biocompatibility of the materials and the cell viability was demonstrated.

Use of quantitative real-time PCR to assess thein vitrosurvival of specific DNA gene sequences of rumen microbes under simulated abomasal conditions

The use of specific DNA sequences (DS) as a microbial marker in post-rumen digesta requires their persistence and integrity throughout gastric digestion. The aim of this study was to evaluate in vitro the survival of microbial DS during gastric digestion and the factors involved. Gastric pH had a highly significant effect on the integrity of DS. pH 4.2 allows for a significant growth of microbes in the medium, but at pH 1.2, almost all of the DS were hydrolysed. In the presence of carboxymethylcellulose, the effect of pH was reduced, pepsin activity was inhibited and gene survival increased considerably. In the simulated abomasal conditions (pH = 2.3, 2 g/l of carboxymethylcellulose, and 40-min retention time), almost all of the bacterial genes and around 78% of the protozoa gene sequences retained their molecular integrity throughout gastric digestion, although factors such as acidity and viscera retention time might compromise the utilisation of DS as a microbial marker.

In-mouth flavour release from milk proteins

The in-mouth release of flavour (2-nonanone) from whey protein isolate (WPI) and sodium caseinate in aqueous solutions, and the influence of the thickener, sodium carboxymethylcellulose (CMC), on the release of 2-nonanone were investigated using proton-transfer-reaction mass spectrometry. During consumption, a significant release of 2-nonanone from WPI (2%) was observed. After swallowing the samples, a substantial amount of flavour was detected in the breath, suggesting that some sample solution remained in the mouth and throat, resulting in a further release of flavour from proteins. In the presence of CMC, a significant release of 2-nonanone from not only WPI but also sodium caseinate was observed, which may be attributable to the increase in viscosity of the solutions. It is likely that a thicker coating of the mouth and throat with the higher viscosity sample after swallowing results in additional release of protein-bound flavour.

Drying and Rehydration of Calcium Alginate Gels

In this paper, we study the rehydration properties of air-dried calcium alginate gel beads. Rehydration is shown to depend on alginate source (i.e. mannuronic to guluronic acid ratio) and the salt concentration in the rehydration medium. Rehydration curves are described adequately by the empirical Weibull equation. Wide-angle X-ray diffraction measurements are performed to obtain information on the microstructure of dried alginate gels. The X-ray diffraction patterns provide evidence for formation of ordered domains in which alginate polymers are laterally associated. Formation of ordered structures during drying is found to have a large impact on rehydration properties. Lateral association of alginate chains is reduced (and rehydration improved) by removing excess calcium ions from the gel beads in a washing step prior to air drying. In addition, rehydration properties of mixed alginate–carboxymethyl cellulose (CMC) gel beads are investigated. The presence of CMC in the gel matrix is found to reduce lateral association of alginate chains during drying and to improve rehydration properties.

The effect of carbohydrate carbon sources on the production of cellulase by Phlebia gigantea

Phlebia gigantea is an aggressive white rot fungus that colonizes conifer wood. The influence of different carbohydrates: glucose, xylose, carboxymethyl cellulose (CMC), microcrystalline cellulose (avicel) and cellobiose were evaluated as carbon sources for the production of cellulase by this saprophytic fungus. Carboxymethyl cellulose gave the highest yield, followed by cellobiose and avicel. Glucose and xylose did not produce any detectable cellulases which suggest the repression of cellulase in presence of these simple carbohydrates by P. gigantea. These results showed that the production of cellulase not only depends on the pH but also on the consumption of carbon sources in medium. The higher yield of cellulase in presence of CMC, the amorphous cellulose, and less in presence of cellobiose the soluble intermediate product of cellulose hydrolysis, indicates the requirement of crystallinity and complexity for the higher yield of cellulase by P. gigantea.

TheAspergillus fumigatuscellobiohydrolase B (cbhB) promoter is tightly regulated and can be exploited for controlled protein expression and RNAi

The utility of the Aspergillus fumigatus cellobiohydrolase cbhB promoter for controlled gene expression has been investigated. cbhB message was present at high levels in the presence of carboxymethylcellulose and undetected in the presence of glucose. A reporter construct using the cbhB promoter showed similar behaviour and gave lower message levels than the Aspergillus nidulans alcA promoter under repressing conditions. An RNAi construct driven by the cbhB promoter was used to down-regulate the alb1 gene; transformants showed low alb1 message levels and a loss-of-function phenotype with carboxymethylcellulose, while both wild-type message levels and phenotype were seen with glucose. The cbhB promoter is therefore tightly controlled and can be exploited for the study of A. fumigatus.

The effect of water-soluble polymers on the stability and rheological properties of suspensions of fibrous activated charcoal

The stability and rheological characteristics of polymer-containing aqueous suspensions of fibrous activated charcoal are determined. It is shown that the improved stability of suspensions is observed in the presence of carboxymethyl cellulose, oxypropyl methyl cellulose, polyvinylpyrrolidone, and a new water-soluble cellulose derivative, whereas the presence of polyacrylamide, poly(acrylic acid), poly(vinyl alcohol), and starch leads to the formation of unstable suspensions having a broad particle size distribution. A correlation between the concentration of dispersed-phase particles corresponding to the transition to non-Newtonian flow and the characteristics of suspension stability (such as the rate of sedimentation, the volume of the sediment, and the particle size distribution) is established. It is suggested that the high degree of charcoal particle surface hydrophilization by polyvinylpyrrolidone and by the water-soluble cellulose derivative is mainly responsible for the stability of the modified suspensions.

Application of model-free kinetics to the study of thermal degradation of polycarbonate

Thermal analysis of polystyrene (PS) particles synthesized in the presence of cetyltrimethylammonium bromide (CTAB) and carboxymethyl cellulose (CMC), with the degree of substitution 0.7 and average molecular mass ( MM ) of 90000 and 250000 g mol -1 was carried out. PS chains grown in the presence of CMC having MM of 90000 g mol -1 presented glass temperature ( T g ) at 375 K, which is in agreement with the literature value. However, the PS chains grown in the presence of longer CMC chains ( MM = 250000 g mol -1 ) presented T g at 352 K. This 23 K decrease in the T g value was caused by the increased polydispersity, which was confirmed by gel permeation chromatography. Thermogravimetry showed five mass loss steps between 298 and 873 K.

Thermal behavior of polystyrene synthesized in the presence of carboxymethyl cellulose

Study of the decomposition kinetics is an important tool for the development of polymer recycling in industrial scale. In this work, parameters such as activation energy, frequency factor and reaction order, were measured under dynamic conditions. Flynn-Wall-Ozawa, Van Krevelen, Horowitz-Metzger, Coats-Redfern, Madhusudanan and Vyazovkin methods were used to determine the kinetic parameters. The analysis of the results obtained by the Coats-Redfern method shows that the thermal degradation process of LDPE and HDPE corresponds to a phase boundary controlled reaction (mechanism R2). This method shows that the reaction order values of LDPE and HDPE are about 0.7 and 0.6, respectively.

Pentlandite–lizardite interactions and implications for their separation by flotation

Magnesium silicate bearing minerals, such as lizardite, are known to cause problems in the flotation of nickel sulfide ores (e.g. pentlandite), by adhering to the valuable mineral particles. Addition of the polymeric dispersant, carboxymethyl cellulose (CMC), has been found to improve nickel recovery during flotation. The interaction between lizardite and pentlandite has been directly investigated using the atomic force microscope (AFM) and electro-kinetic zeta potential determinations, as a function of pH and in the presence of CMC. The lizardite mineral was positively charged, with the zeta potential independent of pH. The magnitude and sign of the pentlandite particles were pH dependent and were negative for pH values above 4.5. At pH values larger than 9, where flotation of nickel sulfide ores is routinely performed, the two minerals are oppositely charged and therefore attract through an electrostatic mechanism. Direct interaction force measurements between pentlandite and lizardite surfaces as a function of pH demonstrate this attractive interaction. Adsorption of CMC at the lizardite/solution interface overcompensates the positive charge on the lizardite particle and its zeta potential is rendered negative. In the presence of CMC, a repulsive interaction force between lizardite and pentlandite was measured in the AFM, which was concluded to be of electro-steric origin. The results explain the flotation behaviour of the minerals performed in this, and previous, studies.

Morphology transcription process from CMC micelles to inorganogel and its effect on the properties of alumina particle

In this study, a carboxymethyl cellulose (CMC)-mediated sol–gel process was developed to synthesize the alumina hydoxide whiskers. During the process, inexpensive inorganic salts were used as precursors and supercritical drying method was used to extract the water in hydrogel. The influences of CMC on the gel formation and the particle morphology were investigated. The results show that the formation of CMC–aluminium hydroxide organic–inorganic hybridgels led to a morphology transcription process from CMC micelles to aluminium hydroxide gel, as a result, the precursor with whiskerious morphology was obtained. Such specific morphology of the precursor delayed phase transformation from transition- to α-alumina greatly, and the ability resistant to sintering was highly enhanced. At presence of CMC, the acicular alumina calcined at 1200 °C for 4 h had surface area of 79.6 m 2 g −1, much higher than the spherical sample (50 m 2 g −1) without CMC. Because of being straightforward, inexpensive and versatile, the approach could be potentially used to prepare other materials with controllable morphologies and might be potentially extended to mass-production.

Synthesis of Stable Polystyrene and Poly(methyl methacrylate) Particles in the Presence of Carboxymethyl Cellulose

The synthesis of polystyrene or poly(methyl methacrylate) in the presence of carboxymethyl cellulose (CMC), a cellulose derivative, was carried out by emulsion polymerization using a cationic surfactant, cetyltrimethylammonium bromide (CTAB). First, the complex formation between CTAB and CMC was studied by surface tension measurements. The polymerization condition chosen was that corresponding to CMC chains fully saturated with CTAB and to the onset of pure surfactant micelle formation, namely, at 0.25 mmol L-1 CTAB and 1.0 g L-1 CMC. The hybrid particles were characterized by ζ potential and light scattering measurements and scanning electron microscopy. All dispersions were stable in the ionic strength of 2.0 mol L-1 NaCl at least for 4 days. The colloidal stability was attributed to the presence of a hydrated CMC layer around the particles. The present procedure brings the advantage of synthesizing and stabilizing particles with functional groups on the surface in a one-step method using very small amo...

Controlling the water content of never dried and reswollen bacterial cellulose by the addition of water‐soluble polymers to the culture medium

AbstractFor the modification of medically useful biomaterials from bacterially synthesized cellulose, fleeces of Acetobacter xylinum have been produced in the presence of 0.5, 1.0, and 2.0% (m/v) carboxymethylcellulose (CMC), methylcellulose (MC), and poly(vinyl alcohol) (PVA), respectively, in the Hestrin‐Schramm culture medium. The incorporation of the water‐soluble polymers into cellulose and their influence on the structure, crystal modifications, and material properties are described. With IR and solid‐state 13C NMR spectroscopy of the fleeces, the presence of the cellulose ethers and an increase in the amorphous parts of the cellulose modifications (NMR results) have been detected. The incorporation is represented by a higher product yield, too. As demonstrated by scanning electron microscopy, a porelike cellulose network structure forms in the presence of CMC and MC. This modified structure increases the water retention ability (expressed as the water content), the ion absorption capacity, and the remaining nitrogen‐containing residues from the culture medium or bacteria cells. The water content of bacterial cellulose (BC) in the never dried state and the freeze‐dried, reswollen state can be controlled by the CMC concentration in the culture solution. The freeze‐dried, reswollen BC‐CMC (2.0%) contains 96% water after centrifugation, whereas standard BC has only 73%. About 98% water is included in a BC‐MC composite in the wet state, and about 93% is included in the reswollen state synthesized in the presence of 0.5, 1.0, or 2.0% MC. These biomaterial composites can be stored in the dried state and reswollen before use, reaching a higher water absorption than pure, never dried BC. The copper ion capacity of BC‐CMC composites increases proportionally with the added amount of CMC. BC‐CMC (0.5%) can absorb 3 times more copper ions than original BC. In the case of 0.5 and 1.0% PVA additions to the culture solution, this polymer cannot be detected in the cellulose fleeces after they are washed. Nevertheless the presence of PVA in the culture medium effects a decreased product yield, a retention of nitrogen‐containing residues in the material during purification, a reduced water absorption ability, and a slightly higher copper ion capacity in comparison with original BC. The water content of freeze‐dried, reswollen BC‐PVA (0.5%) is only 62%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 463–470, 2004

Detecting cellulase and esterase enzyme activities encoded by novel genes present in environmental DNA libraries.

A genomic DNA library was made from the alkaliphilic cellulase-producing Bacillus agaradhaerans in order to prove our technologies for gene isolation prior to using them with samples of DNA isolated directly from environmental samples. Clones expressing a cellulase activity were identified and sequenced. A new cellulase gene was identified. Genomic DNA libraries were then made from DNA isolated directly from the Kenyan soda lakes, Lake Elmenteita and Crater Lake. Crater Lake clones expressing a cellulase activity and Lake Elmenteita clones expressing a lipase/esterase activity were identified and sequenced. These were encoded by novel genes as judged by DNA sequence comparisons. Genomic DNA libraries were also made from laboratory enrichment cultures of Lake Nakuru and Lake Elmenteita samples. Selective enrichment cultures were grown in the presence of carboxymethylcellulose (CMC) and olive oil. A number of new cellulase and lipase/esterase genes were discovered in these libraries. Cellulase-positive clones from Lake Nakuru were isolated at a frequency of 1 in 15,000 from a library made from a CMC enrichment as compared to 1 in 60,000 from a minimal medium enrichment. Esterase/lipase-positive clones from Lake Elmenteita were isolated with a frequency of 1 in 30,000 from a library made from an olive-oil enrichment as compared to 1 in 100,000 from an environmental library.

Activity Enhancement of Cel5Z from Pectobacterium chrysanthemi PY35 by Removing C-Terminal Region

The phytopathogenic bacterium Pectobacteium chrysanthemi PY35 secretes Cel5Z endoglucanase belonging to the glycoside hydrolase family 5 of EC 3.2.1.4. The mutation of cel5Z::Ω gene was constructed by cloning the 2.0-kb SmaI fragment containing the streptomycin/spectinomycin-resistance gene of pHP45Ω into the BalI site of pPY100. The insertion of Ω fragment generated a new stop codon, removing the Ser/Thr-rich linker region and the cellulose binding domain (CBD) in the C-terminal region of cel5Z gene. By subsequent subcloning from this 4.9-kb fragment (pPY1001), a 1.0-kb (pPY1002) fragment was obtained and designated as cel5Z::Ω. The cel5Z::Ω gene had an open reading frame (ORF) of 1011 bp, encoding 336 amino acids, starting with an ATG codon and ending with a new TGA stop codon. The molecular mass of the Cel5Z::Ω protein in E. coli transformant appeared to be 32 kDa by SDS–PAGE analysis in the presence of carboxymethyl-cellulose (CMC). The Cel5Z::Ω protein hydrolyzed CMC with 1.7-fold higher activity than the intact Cel5Z cellulase.

Modification of the microstructural and physical properties of konjac glucomannan-based films by alkali and sodium carboxymethylcellulose

Edible films were cast from konjac glucomannan (KGM) solutions, with or without added alkali (KOH) and/or sodium carboxymethylcellulose (CMC). Four types of KGM-based films (KGM, KGM–KOH, KGM–CMC and KGM–CMC–KOH) were produced and characterized by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), moisture sorption, water vapour permeability (WVP), and tensile tests. Tensile properties were studied as a function of water activity ( a w) over the range from 0.22 to 0.84. SEM revealed that films, with and without KOH, exhibited cross-sectional lamellar structures running perpendicular and parallel, respectively, to the film surface. Alkali treatment produced films with enhanced crystallinity, lower water-sorptive capacity (WSC) and WVP, and higher tensile properties. These effects were attributed to alkaline deacetylation of KGM molecules which permitted greater intermolecular interactions. The presence of CMC appeared to suppress crystallinity of native KGM films, but enhanced that of deacetylated KGM films. Films incorporating CMC exhibited higher WSC and WVP, but variable tensile properties depending on alkali treatment and a w. The tensile properties of all KGM-based films were profoundly affected by a w. Tensile modulus (TM) of all films were antiplasticized as a w was increased from 0.22 to 0.43, but tensile strength (TS) was generally plasticized by water. Tensile elongation of KGM, KGM–KOH, and KGM–CMC–KOH films was generally much less sensitive to water. However, KGM–CMC films exhibited minimum elongation, attributed to antiplasticization by water, over the intermediate a w range from 0.43 to 0.69. KGM–CMC–KOH films exhibited the highest TM and TS at any particular a w.

Effects of food gums on viscosities of starch suspensions during pasting

Pasting curves of starches in gum (hydrocolloid) solutions at low concentrations (starch 3.6%, gum 0.4%) were produced with a Brookfield viscometer. Gums produced a variety of effects on viscosities of starches during starch pasting (increase or decrease greatly or slightly or no effect). A viscosity increase before the normal starch pasting temperature was detected for normal maize starch in the presence of carboxymethylcellulose (CMC), gellan, xanthan, guar gum, and sodium alginate. Waxy maize, waxy rice, tapioca, regular rice, potato, and wheat starches gave mixed responses. It appeared that interactions between certain leached molecules, primarily amyloses, and certain gums were responsible for the viscosity increase occurring before starch pasting. The pasting peak viscosity of potato starch was greatly decreased by negatively charged gums (CMC, carageenans, alginate, xanthan). The repelling forces between the phosphate groups on potato starch and the negative charges on molecules of these gums were hypothesized to be the cause. This hypothesis was supported by results from similar systems (potato starch plus salt solution and phosphorylated normal maize starch plus anionic gums), both of which systems also produced lower peak viscosities. It was found, by microscopic examination of potato starch heated to 95 °C in solutions of ionic gums without shear, that the gums altered the granule pasting process.

Effects of rheological change by addition of carboxymethylcellulose in culture media of an air-lift fermentor on poly-D-3-hydroxybutyric acid productivity in autotrophic culture of hydrogen-oxidizing bacterium, Alcaligenes eutrophus

The effects of rheological change by addition of sodium carboxymethylcellulose (CMC) to culture medium in an air-lift-type fermentor on autotrophic production of poly-(D-3-hydroxybutyric acid) [P(3HB)] by two-stage culture of Alcaligenes eutrophus is investigated. Addition of 0.05% CMC increased P(3HB) production rate during the P(3HB) accumulation phase to twice that of the control culture. It was thought that addition of a small amount of CMC was beneficial for production of P(3HB) employing the air-lift fermentor under safe autotrophic culture conditions in wich oxygen concentration was maintained below 6.9% (v/v). the volumetric mass transfer coefficient (K(L)a) observed in the presence of CMC is shown to correlated with the P(3HB) production rate obtained. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 529-533, 1997.