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Glutaraldehyde
Selected AbstractsCovalent immobilization of ,-galactosidase on carrageenan coated with chitosanJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009Magdy M.M. Elnashar Abstract ,-Galactosidase was covalently immobilized to carrageenan coated with chitosan for the hydrolysis of lactose. The chitosan-carrageenan polyelectrolyte interaction was found to be dependent on the chitosan pH. At pH 4, the chitosan reached its maximum binding of 28.5% (w/w) where the chitosan surface density was 4.8 mg chitosan/cm2 g of carrageenan gel disks, using Muzzarelli method. Glutaraldehyde was used as a mediator to incorporate new functionality, aldehydic carbonyl group, to the bio-polymers for covalent attachment of ,-galactosidase. The enzyme was covalently immobilized to the biopolymer at a concentration of 2.73 mg protein per g of wet gel. FTIR proved the incorporation of the aldehydic carbonyl group to the carrageenan coated with chitosan at 1720 cm,1. The optimum time for enzyme immobilization was found to be 16 h, after which a plateau was reached. The enzyme loading increased from 2.65 U/g (control gel) to 10.92 U/g gel using the covalent technique. The gel's modification has shown to improve the carrageenan gel thermal stability as well as the immobilized enzyme. For example, the carrageenan gel treated with chitosan showed an outstanding thermal stability at 95°C compared with 35°C for the untreated carrageenan gel. Similarly, the immobilization process shifted the enzyme's optimum temperature from 50°C for the free enzyme towards a wider temperature range 45,55 °C indicating that the enzyme structure is strengthened by immobilization. In brief, the newly developed immobilization method is simple; the carrier is cheap, yet effective and can be used for the immobilization of other enzymes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Cryo-sectioning and chemical-fixing ultramicrotomy techniques for imaging rubber latex particle morphologyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2004Nadaraja Subramaniam Abstract Two methods adapted from biological microscopy are described for a new application in imaging the morphology of rubbery latex particles. In the first method, a drop of latex is frozen in liquid nitrogen, sectioned with a diamond knife and vapour-stained with osmium tetroxide, then viewed by transmission electron microscopy. When applied to latexes made by emulsion polymerization of methyl methacrylate in a natural rubber latex seed, inclusions are clearly visible. A chemical fixation method is then described for imaging the morphology of such rubbery latex particles. Glutaraldehyde is added to the latex, followed by osmium tetroxide. The sample is then dehydrated in ethanol, epoxy resin added, and the sample cured, ultramicrotomed, and imaged with transmission electron microscopy. An inclusion morphology is again clearly seen. Microsc. Res. Tech. 63:111,114, 2004. © 2004 Wiley-Liss, Inc. [source] Elucidation of the mechanism and end products of glutaraldehyde crosslinking reaction by X-ray structure analysisBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2007Yariv Wine Abstract Glutaraldehyde has been used for several decades as an effective crosslinking agent for many applications including sample fixation for microscopy, enzyme and cell immobilization, and stabilization of protein crystals. Despite of its common use as a crosslinking agent, the mechanism and chemistry involved in glutaraldehyde crosslinking reaction is not yet fully understood. Here we describe feasibility study and results obtained from a new approach to investigate the process of protein crystals stabilization by glutaraldehyde crosslinking. It involves exposure of a model protein crystal (Lysozyme) to glutaraldehyde in alkaline or acidic pH for different incubation periods and reaction arrest by medium exchange with crystallization medium to remove unbound glutaraldehyde. The crystals were subsequently incubated in diluted buffer affecting dissolution of un-crosslinked crystals. Samples from the resulting solution were subjected to protein composition analysis by gel electrophoresis and mass spectroscopy while crosslinked, dissolution resistant crystals were subjected to high resolution X-ray structural analysis. Data from gel electrophoresis indicated that the crosslinking process starts at specific preferable crosslinking site by lysozyme dimer formation, for both acidic and alkaline pH values. These dimer formations were followed by trimer and tetramer formations leading eventually to dissolution resistant crystals. The crosslinking initiation site and the end products obtained from glutaraldehyde crosslinking in both pH ranges resulted from reactions between lysine residues of neighboring protein molecules and the polymeric form of glutaraldehyde. Reaction rate was much faster at alkaline pH. Different reaction end products, indicating different reaction mechanisms, were identified for crosslinking taking place under alkaline or acidic conditions. Biotechnol. Bioeng. 2007;98:711,718. © 2007 Wiley Periodicals, Inc. [source] ChemInform Abstract: First Synthesis of Propano-dibenzo[1,3]dioxocin Type Compounds from Condensation of p-Substituted Phenol Derivatives with Glutaraldehyde in Trifluoroacetic Acid.CHEMINFORM, Issue 37 2002Ali Rahmatpour Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Electrochemistry of Mitochondria: A New Way to Understand Their Structure and FunctionELECTROANALYSIS, Issue 14 2008Jing Zhao Abstract In this article, electrochemistry of mitochondria is achieved. Cyclic voltammograms of freshly prepared mitochondria were obtained by immobilizing mitochondria together with glutaraldehyde and bovine serum albumin on the surface of a pyrolytic graphite electrode. Two pairs of redox peaks could be observed which were ascribed to the electron transfer reactions of cytochrome c and FAD/FADH2. Study of submitochondrial particles was also conducted, which could confirm the results of the study of the entire mitochondria. The redox wave of NADH could be obtained due to the destruction of the membrane of mitochondria. We have also checked the function of succinate in mitochondria by employing the electrochemical method. This work is not only the first to be able to obtain the direct electrochemistry of mitochondria, but is also beneficial to the further understanding of the structure and function of mitochondria in vitro. [source] Voltammetric Sensor for Sodium Nitroprusside Determination in Biological Fluids Using Films of Poly- L -LysineELECTROANALYSIS, Issue 9 2007Claudece Pereira, Francisco Abstract Sodium nitroprusside (NP), a commercial vasodilator, can be pre-concentrated on vitreous carbon electrode modified by films of 97.5%: 2.5% poly- L -lysine (PLL): glutaraldehyde (GA). This coating gives acceptable anion exchange properties whilst giving the required improvement of adhesion to the glassy carbon electrode surface. Linear response range and detection limit on nitroprusside in B-R buffer pH,4.0, were 1×10,6 to 2×10,5 mol L,1 and 1×10,7 mol L,1, respectively. The repeatability of the proposed sensor, evaluated in term of relative standard deviation, was measured as 4.1% for 10 experiments. The voltammetric sensor was directly applied to determination of nitroprusside in human plasma and urine samples and the average recovery for these samples was around 95,97% without any pre treatment. [source] Electrooxidation of DNA at Glassy Carbon Electrodes Modified with Multiwall Carbon Nanotubes Dispersed in ChitosanELECTROANALYSIS, Issue 7-8 2007Soledad Bollo Abstract We report on the analytical performance of glassy carbon (GCE) electrodes modified with a dispersion of multiwall carbon nanotubes (CNT) in chitosan (CHIT) for the quantification of DNA. The electroanalytical response of the resulting electrodes was evaluated using differential pulse voltammetry, while the electrochemical reactivity of the film surface was characterized using scanning electrochemical microscopy. Different treatments of the modified GCE were evaluated to improve the stability of the film and the accumulation of DNA. The guanine oxidation signal of double stranded calf-thymus DNA after 3-min accumulation was 20 times higher at GCE/CHIT-CNT cross-linked with glutaraldehyde (GTA) than at bare GCE, while the peak potential was around 45,mV less positive. The guanine oxidation signal demonstrated to be highly reproducible, with 3.4% RSD for 5 different electrodes. The treatment with sodium hydroxide demonstrated to be not effective since the resulting films were less stable and the guanine oxidation signal was ten times smaller compared to electrodes prepared with the GTA treated films. The effect of chitosan molecular weight used to prepare the dispersion and the amount of carbon nanotubes dispersed were evaluated. The response of single stranded DNA and oligo(dG)15 is also discussed. [source] Glucose Biosensor Mediated by 1,2-Diferrocenylethane in a Sono-Gel Composite ElectrodeELECTROANALYSIS, Issue 2-3 2007Barbara Ballarin Abstract An amperometric glucose biosensor was constructed based on a renewable carbon composite sono-gel matrix incorporating 1,2-diferrocenylethane as electron transfer mediator between the electrode and the active site of glucose oxidase. The enzyme was immobilized on the electrode surface by cross-linking with glutaraldehyde and bovine serum albumin. The process parameters for the fabrication of the biosensor and the influence of various experimental conditions (i.e., pH, temperature, operating potential) were investigated. Cyclic voltammetry and amperometric measurements were used to study the response of the glucose sensor, which displayed fast response time and good reproducibility. The analytical performances and the apparent Michaelis-Menten constant of the biosensor were evaluated. [source] Development of Novel Glucose and Pyruvate Biosensors at Poly(Neutral Red) Modified Carbon Film Electrodes.ELECTROANALYSIS, Issue 8 2006Application to Natural Samples Abstract Amperometric biosensors based on the corresponding oxidase enzyme with poly(neutral red) redox mediator have been developed for the determination of glucose and pyruvate. The enzymes have been immobilized on top of poly(neutral red) modified carbon film electrodes with glutaraldehyde as the cross-linking agent. The biosensors were characterized by cyclic voltammetry and by electrochemical impedance spectroscopy. The glucose biosensor exhibited a linear response in the range 90,,M to 1.8,mM with a detection limit of 22,,M and the pyruvate biosensor in the range 90 to 600,,M with a detection limit of 34,,M. The relative standard deviations were found to be 2.1% (n=3) and 2.8% (n=4) respectively. The interference effects of various compounds were also studied. The glucose content of several types of wine and the amount of pyruvate in onion and garlic were determined and the results were compared with those obtained by standard spectrophotometric methods. [source] A Lactulose Bienzyme Biosensor Based on Self-Assembled Monolayer Modified ElectrodesELECTROANALYSIS, Issue 17 2004Susana Campuzano Abstract A bienzyme biosensor in which the enzymes ,-galactosidase (,-Gal), fructose dehydrogenase (FDH), and the mediator tetrathiafulvalene (TTF) were coimmobilized by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer on a gold disk electrode, is reported. The working conditions selected were Eapp=+0.10,V and (25±1),°C. The useful lifetime of one single TTF-,-Gal-FDH-MPA-AuE was surprisingly long, 81,days. A linear calibration plot was obtained for lactulose over the 3.0×10,5,1.0×10,3,mol L,1 concentration range, with a limit of detection of 9.6×10,6,mol L,1. The effect of potential interferents (lactose, glucose, galactose, sucrose, and ascorbic acid) on the biosensor response was evaluated. The behavior of the SAM-based biosensor in flow-injection systems in connection with amperometric detection was tested. The analytical usefulness of the biosensor was evaluated by determining lactulose in a pharmaceutical preparation containing a high lactulose concentration, and in different types of milk. Finally, the analytical characteristics of the TTF-,-Gal-FDH-MPA-AuE are critically compared with those reported for other recent enzymatic determinations of lactulose. [source] A New Polyphenol Oxidase Biosensor Mediated by Azure B in Laponite Clay MatrixELECTROANALYSIS, Issue 19 2003Dan Shan Abstract Amperometric biosensor based on the entrapment of polyphenol oxidase within a laponite clay coating and cross-linked by glutaraldehyde is described for catechol detection. Laponite provides a hydrophilic enzyme surrounding increasing the long term stability of the biosensor compared to the corresponding biosensors obtained by chemical cross-linking of PPO with glutaraldehyde. Azure B, a cationic dye exchanged within the clay matrix, is used as an electron shuttle allowing the mediated detection of phenol derivatives at ,0.05 V. The detection limits obtained with the optimized biosensor configuration for catechol, p -cresol and phenol are 1, 1 and 17,nM, respectively. [source] Carboxylic multi-walled carbon nanotubes as immobilized stationary phase in capillary electrochromatography,ELECTROPHORESIS, Issue 18 2008Lorena Sombra Abstract Carboxylic multi-walled carbon nanotubes (c-MWNT) have been immobilized into a fused-silica capillary for capillary electrochromatography. The c-MWNT were successfully incorporated after the silanization and coupling with glutaraldehyde on the inner surface of the capillary. The electrochromatographic features of the c-MWNT immobilized stationary phase have been evaluated for the analysis of different compounds of pharmaceutical interest. The results indicated high electrochromatographic resolution, good capillary efficiency and retention factors. In addition, highly reproducible results between runs, days and capillaries were obtained. [source] Comparison of two glutaraldehyde immobilization techniques for solid-phase tryptic peptide mapping of human hemoglobin by capillary zone electrophoresis and mass spectrometryELECTROPHORESIS, Issue 9 2004Isabelle Migneault Abstract Stabilization of proteolytic enzymes, especially by immobilization, is of considerable interest because of their potential applications in medicine and the chemical and pharmaceutical industries. We report here a detailed comparison of two procedures for trypsin immobilization using the same homobifunctional agent, glutaraldehyde, for the purpose of peptide mapping. These methods include covalent coupling either to controlled pore glass (solid support) or via a cross-linking reaction (without any solid support). The immobilized trypsin preparations were characterized by the determination of immobilization efficiency, which ranged from 68 to > 95%, and measurement of apparent kinetic parameters toward a synthetic peptide-like substrate. Batch digestions of whole denaturated human normal adult hemoglobin (HbA) were performed to obtain peptide maps by capillary zone electrophoresis (CZE). Migration time reproducibility of the CZE maps was excellent, with a mean relative standard deviation of 1.5%. Moreover, the two immobilized enzyme preparations showed excellent reproducibility for repeated digestions. Matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry was also used for peptide mass mapping of denaturated HbA digested using the two immobilized trypsin preparations. Even though the two immobilized trypsin preparations do not behave identically, similar sequence coverages of 57% and 61% (for the two HbA chains merged) were achieved for the support-based and cross-linked trypsin preparations, respectively. [source] A simple polyacrylamide gel electrophoresis procedure for separation of polyamidoamine dendrimersELECTROPHORESIS, Issue 16 2003Ajit Sharma Abstract A simple, inexpensive, and rapid electrophoresis technique was developed for use as a routine tool for evaluating purity of polyamidoamine (PAMAM) dendrimers. A variety of factors influencing migration of generations 0,7 dendrimers on nongradient polyacrylamide gels were evaluated. The low generation dendrimers were found to be very sensitive to diffusion during or after electrophoresis. The proposed method incorporates steps that minimize diffusion, in order to obtain improved resolution and sensitivity, especially for the lower-molecular-weight dendrimers. This was accomplished by inclusion of a dendrimer fixation step with glutaraldehyde and performing the electrophoresis separation, fixation, staining, and destaining at 4°C. PAMAM dendrimer separation was studied under basic and acidic conditions. Electrophoresis under acidic conditions gave increased resolution and sensitivity over separation at alkaline pH. Oligomers and trailing generations could be clearly separated and visualized under these conditions. The smallest PAMAM dendrimer, generation 0, was visible at 1.5 ,g under the optimized acidic conditions. With slight modifications, this technique should be applicable to separation of other water-soluble dendrimers. [source] Development of a bacterial challenge test for gnotobiotic sea bass (Dicentrarchus labrax) larvaeENVIRONMENTAL MICROBIOLOGY, Issue 2 2009K. Dierckens Summary The use of probiotic microorganisms in aquaculture is gaining a lot of interest. Gnotobiotic model systems are required in order to fully understand the effects and modes-of-action of these microorganisms, as the native microbial communities present in non-sterile animals can lead to false conclusions. In this study, a gnotobiotic sea bass larvae (Dicentrarchus labrax) test system was developed. In order to obtain bacteria-free animals, the eggs were disinfected with glutaraldehyde and subsequently incubated in a solution of rifampicin and ampicillin. Axenity was confirmed using culture-dependent and -independent techniques. The gnotobiotic larvae were fed axenic Artemia sp. from 7 days after hatching onwards. In the challenge test, one of the three opportunistic pathogens, Aeromonas hydrophila, Listonella anguillarum serovar O1 and O2a, was added to the model system via the water and encapsulated in Artemia sp. Only serovar O2a led to increased mortality in the sea bass larvae. The presented gnotobiotic model can be used for research on, among others, reciprocal metabolic effects between microorganisms and the host (e.g. as measured by gene expression), immunostimulants, pharmacological research and the histological development of the gastrointestinal tract and growth of larvae. [source] Spectroscopic investigation of the function of aqueous 2-hydroxyethylmethacrylate/glutaraldehyde solution as a dentin desensitizerEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2006Chuangye Qin Fourier-transform (FT)-Raman and -infrared (IR) spectroscopy were employed to investigate the function of the aqueous 2-hydroxyethylmethacrylate/glutaraldehyde solution (Gluma) as a desensitizer. 2-Hydroxyethylmethacrylate (HEMA), glutaraldehyde (GA), and the mixture of HEMA/GA (i.e. Gluma) were used to interact with dentin, collagen, hydroxyapatite (HAP), and bovine serum albumin (BSA) individually. All the interactions were monitored by an FT-Raman spectrometer. FT-IR spectroscopy was also used in this study. The results show that HEMA could be absorbed by dentin and collagen; GA could cross-link collagen and BSA; and when BSA was added to Gluma, polymerization of HEMA occurred. The results suggest that Gluma acts as a desensitizer whereby, first, GA reacts with part of the serum albumin in dentinal fluid, which induces a precipitation of serum albumin, then, second, a reaction of GA with serum albumin induces polymerization of HEMA. The function of Gluma as a desensitizer to block dentinal tubules occurs via these two reactions. [source] Dispersive Effects in Chemomechanical Reactions with Polyallylamine-Derived HydrogelsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2008Kazuaki Kato Abstract Volume changes of polyallylamine-derived hydrogels crosslinked with glutaraldehyde are determined with a large variety of effector compounds. Monocarboxylic effectors lead to smaller contractions, in contrast to dicarboxylate structures, which allow more effective non-covalent crosslinking between the positively charged nitrogen centers of the polymer backbone. Electroneutral compounds lead to negligible changes, whereas effectors with either a large p -moiety like in naphthoic acid or phenyl derivatives with polarizable substituents induce large contractions. This finding is in line with significant contributions of van der Waals interactions between the effectors within the hydrogel. Chemomechanical differences between regioisomeric effectors such as p - and o -nitrobenzoic acid are in agreement with independent results of dispersive interactions in related complexes. The volume decrease corresponds almost entirely to the gravimetrically determined water content of the gels. The acidity profile shows a strong contraction above pH 10, which is consistent with the known pK value of such polyamines. NMR spectra of the gels indicate strong binding of the effectors by line broadening, which is significant only for the chemomechanically active compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Carbon Nanotubes on Polymeric Microcapsules: Free-Standing Structures and Point-Wise Laser OpeningsADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Alexey M. Yashchenok Abstract Single-wall carbon nanotubes modified by anionic polyelectrolyte molecules are embedded into the shells of microcapsules. Carbon nanotubes serve as rigid rods in a softer polymeric capsule, which forms a free-standing shell upon treatment with glutaraldehyde and subsequent drying. The embedded carbon nanotubes exhibit a broad absorption in the UV,near-infrared part of the spectrum, and that allows point-wise activation and opening of the microcapsules by laser. Raman signal analysis shows changes of carbon-nanotube-specific lines after high-power laser irradiation, which is characteristic of the formation of disordered carbonlike structures. These polyelectrolyte/carbon nanotube composite capsules represent a novel light-addressable type of microcontainers. [source] Signal-On Electrochemiluminescence Biosensors Based on CdS,Carbon Nanotube Nanocomposite for the Sensitive Detection of Choline and AcetylcholineADVANCED FUNCTIONAL MATERIALS, Issue 9 2009Xiao-Fei Wang Abstract This work describes for the first time signal-on electrochemiluminescence (ECL) enzyme biosensors based on cadmium sulfide nanocrystals (CdS NCs) formed in situ on the surface of multi-walled carbon nanotubes (MWCNTs). The MWCNT,CdS can react with H2O2 to generate strong and stable ECL emission in neutral solution. Compared with pure CdS NCs, the MWCNT,CdS can enhance the ECL intensity by 5.3-fold and move the onset ECL potential more positively for about 400,mV, which reduces H2O2 decomposition at the electrode surface and increases detection sensitivity of H2O2. Furthermore, the ECL intensity is less influenced by the presence of oxygen in solution. Benefiting from these properties, signal-on enzyme-based biosensors are fabricated by cross-linking choline oxidase and/or acetylcholine esterase with glutaraldehyde on MWCNT,CdS modified electrodes for detection of choline and acetylcholine. The resulting ECL biosensors show wide linear ranges from 1.7 to 332,µM and 3.3 to 216,µM with lower detection limit of 0.8 and 1.7,µM for choline and acetylcholine, respectively. The common interferents such as ascorbic acid and uric acid in electrochemical enzyme-based biosensors do not interfere with the ECL detection of choline and acetylcholine. Furthermore, both ECL biosensors possess satisfying reproducibility and acceptable stability. [source] Identification and Characterization of an Organic Solvent Tolerance Gene in Helicobacter pyloriHELICOBACTER, Issue 1 2007Hung-Chuan Chiu Abstract Background:, Pre-cleaning and soaking in glutaraldehyde is the necessary procedure to disinfect endoscopes. However, some chemical-solvent-tolerant bacteria may survive after incomplete endoscopic disinfection. The goal of this study was to identify glutaraldehyde resistance-related genes in Helicobacter pylori. Materials and Methods:, ,-Zap phagemid expression library of H. pylori strain NTUH-C1 was selected with 0.1% glutaraldehyde. The minimal inhibitory concentration (MIC) of glutaraldehyde-resistant DNA fragments of H. pylori NTUH-C1 strain were determined. Imp/OstA recombinant protein was expressed, purified, and used to generate anti-Imp/OstA polyclonal antibody. Imp/ostA knockout, deletion, and complementation strains were constructed. The function of Imp/OstA was monitored by organic solvent tolerance assay, antibiotics susceptibility test, and n -phenylnapthylamine assay. Results:, Using Imp/ostA polyclonal antibody against cell lysate of wild-type and imp/ostA mutant showed that it is not essential in H. pylori. Organic solvent tolerance assay demonstrated the role of Imp/ostA in n-hexane tolerance. MIC test showed that the mutation of imp/ostA was susceptible to hydrophobic and ,-lactam antibiotics. NPN assay demonstrated that the level of outer membrane permeability was increased by 50% in mutant strain comparing to wild-type strain (p < .001). Conclusions:, We have identified an Imp/OstA protein that was associated with glutaraldehyde resistance in our clinical strain H. pylori NTUH-C1 by screening of ,-Zap expression library. Disruption of this protein results in altering membrane permeability, sensitivity to organic solvent, and susceptibility to antibiotics. [source] Development of hydrogel patch for controlled release of alpha-hydroxy acid contained in tamarind fruit pulp extractINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2005J. Viyoch Synopsis The aim of this study was to develop hydrogel patch using crosslinked chitosan,starch as polymeric matrix for controlling the release of the natural alpha-hydroxy acid (AHA) contained in the extract of tamarind's fruit pulp. The chitosan (MW 100 000) was blended with corn, tapioca or rice starch in various ratios and then crosslinked with glutaraldehyde. The physical characteristics, mechanical resistance, bio-adhesion property and surface morphology of the prepared hydrogel patches with and without the extract were investigated. The release patterns of the hydrogel patches containing the extract were investigated by measuring the amount of tartaric acid, a major AHA present in the tamarind's fruit pulp extract, accumulated in the receptor medium of the vertical diffusion cell at various time intervals over a period of 6 h. The results indicated that the formulations of chitosan : corn starch 4.5 : 0.5 with glutaraldehyde 0.02% w/w (C4.5C0.5G0.02) or 0.04% w/w (C4.5C0.5G0.04), chitosan : tapioca starch 4.5 : 0.5 with glutaraldehyde 0.04% w/w (C4.5T0.5G0.04) or 0.05% w/w (C4.5T0.5G0.05), and chitosan : rice starch 4.5 : 0.5 with glutaraldehyde 0.04% w/w (C4.5R0.5G0.04) and chitosan : rice starch 4.0 : 1.0 with glutaraldehyde 0.03% w/w (C4.0R1.0G0.03) provided the flexible and elastic patches with good bio-adhesive property. The tensile strength values ranged from 5 to15 N mm,2 and the elasticity ranged from 30 to 60%. The addition of the extract in these formulations significantly increased the tensile strength values of the obtained patches. The patch of C4.0R1.0G0.03 formulation containing the extract showed relatively highest porosity, corresponding to its highest amount (12.02 ± 0.33 mg) and rate (0.452 ± 0.012 mg mm,2 min,1/2) of tartaric acid released. The amounts of tartaric acid released from the developed hydrogel patches were proportional to a square root of time (Higuchi's model), particularly the release from C4.0R1.0G0.03 (R2, 0.9978 ± 0.0020) and C4.5R0.5G0.04 (R2, 0.9961 ± 0.0024) patches. Résumé Le but de cette étude était de développer un patch hydrogel en utilisant, en tant que matrice polymère, un mélange chitosane/amidon réticulé pour le contrôle du relargage d', -hydroxyacide naturel contenu dans l'extrait de la pulpe du fruit du tamarinier. Du chitosane (MW 100 000) a été mélangéà des farines de maïs, de tapioca ou de riz dans différentes proportions, les mélanges ont été réticulés avec du glutaraldéhyde. Les caractéristiques physiques, résistance mécanique, propriétés de bio adhésion et morphologie de surface des patchs hydrogels préparés avec et sans extrait ont étéétudiées. Le profil de relargage des patchs hydrogels contenant l'extrait a étéétudié en mesurant la quantité d'acide tartarique, , -aminoacide majoritaire présent dans l'extrait, accumulé dans le milieu récepteur d'une cellule à diffusion verticale en fonction du temps sur une période de 6 heures. Les résultats ont montré que les formulations contenant: ,,un mélange chitosane/amidon de maïs dans un rapport 4.5 : 0.5 réticulé avec 0.02% ou 0.04% poids/poids de glutaraldéhyde (respectivement C4.5C0.5G0.02 et C4.5 C0.5 G0.04) ou ,,un mélange de chitosane/amidon de tapioca dans un rapport 4.5 : 0.5 réticulé avec 0.04% ou 0.05% poids/poids de glutaraldéhyde (C4.5T0.5 G0.04ou C4.5 T0.5 G0.05) ,,ainsi que le mélange chitosane/amidon de riz dans un rapport 4.5 : 0.5 réticulé avec 0.04% poids/poids de glutaraldehyde (C4.5R0.5 G0.04) ,,et le mélange chitosane/amidon de riz dans un rapport 4.0 : 1.0 réticulé avec 0,03% poids/poids de glutaraldehyde (C4.0 R1.0 G0.03) conduisaient à des patchs flexibles et élastiques avec de bonnes propriétés bio adhésives. Leur résistance mécanique varie de 5 à 15 N/m2 et leur élasticité de 30 à 60%. L'addition de l'extrait de fruit à ces formules augmente significativement la résistance mécanique des patchs. Le patch C4.0R1.0 G0.03 contenant l'extrait montre la plus grande porosité correspondant à la quantité d'acide tartarique relargué la plus élevée (12.02 ± 0.33 mg), ainsi qu'à la plus grande vitesse de relargage (0.452 ± 0.012 mg mm- 2 mn- 1/2). Les quantités d'acide tartarique relarguées à partir de patchs hydrogels développés sont proportionnelles à la racine carrée du temps (modèle d'Higuchi), en particulier pour les patchs C4.0 R1.0G0.03 (R2, 0.9978 ± 0.0020) et C4.5R0.5 C0.004 (R2, 0.9061 ± 0.0024). [source] A clonal cutaneous CD30+ lymphoproliferative eruption in a patient with evidence of past exposure to hepatitis EINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 7 2000Freddye M. Lemons-Estes CDR, MC USN The patient was a 52-year-old white man who had worked in remote areas of the world during the past 2 years, including an extended period in rural areas of Central Africa and in Central and South America. He had no acute illnesses during the 2-year period except for rare, mild, upper respiratory tract infections. For approximately 1 year, however, he had developed recurrent, papular-vesicular, slightly painful lesions on the fingers and palms, that spontaneously healed over weeks to months ( Fig. 1). The patient had no other concurrent illnesses and no abnormal laboratory findings, except for positive enzyme-linked immunoabsorbent assay (ELISA) for immunoglobulin G (IgG) antibodies for hepatitis E virus (HEV) using a recombinant expressed HEV antigen (Genelabs Technologies, Inc., San Antonio). Prolonged treatment with minocycline did not appear to moderate the lesions. At approximately 2.5 years after the development of his first cutaneous lesion, however, the patient reported that he had had no new lesions for over 3 months. Figure 1. Vesicular ,lesion on the finger which regressed over a period of weeks A biopsy specimen showed an intraepidermal vesicle with prominent epidermal necrosis and reticular degeneration ( Fig. 2). Within the epidermis, there was a dense infiltrate of lymphoid cells. The majority of these cells were pleomorphic with prominent nucleoli and frequent mitotic figures ( Fig. 3). Sheets of atypical cells were found in the subjacent dermis. The infiltrate extended down into the reticular dermis. With extension into the dermis, the infiltrate became more polymorphous with more small lymphoid cells, large numbers of eosinophils, and some plasma cells located more deeply. Figure 2. Intraepidermal ,blister showing reticular degeneration and marked epidermotrophism of large atypical cells with extension into the dermis with a mixed infiltrate containing eosinophils and plasma cells (30×) Figure 3. Intraepidermal ,infiltrate of large atypical cells with extension into the dermis with a mixed infiltrate containing eosinophils and plasma cells (400×) Immunohistochemical stains for CD3 (DAKO), CD4 (Becton Dickinson), CD8 (Becton Dickinson), CD15 (LeuM1, Becton Dickinson), CD20 (L-26, DAKO), CD30 (Ber-H2, DAKO), CD45RO (UCHL1, DAKO), S-100 protein (DAKO), T-cell intracellular antigen (TIA) (Coulter), epithelial membrane antigen (EMA) (DAKO), KP-1 (CD68, DAKO), MAC-387 (DAKO), Epstein,Barr virus (EBV) latent membrane antigen-1 (LMP-1, DAKO), and EBV-encoded nuclear antigen 2 (EBNA2, DAKO) were performed on formalin-fixed tissue using the ABC method with DABA as the chromagen. CD3 showed diffuse membrane staining of the large atypical lymphoid cells, as well as the majority of the small lymphoid cells ( Fig. 4). CD4 showed positive membrane staining of the large atypical lymphoid cells and the majority of the small lymphoid cells. CD8 showed only scattered light membrane staining of small lymphoid cells. CD15 was negative, and CD20 showed foci of groups of small lymphoid cells mainly within the reticular dermis. CD30 showed positive membrane and paranuclear staining of the large atypical cells, most abundant within the epidermis and papillary dermis ( Fig. 5). CD45RO showed positive membrane staining of the large atypical cells and the majority of the small lymphoid cells. S-100 protein showed increased dendritic cells within the surrounding viable epidermis and the subjacent papillary dermis ( Fig. 6). TIA showed granular staining in the large atypical lymphoid cells and only rare staining in small lymphoid cells ( Fig. 7). EMA staining was essentially negative. KP-1 showed only scattered positive cells mainly in the lower papillary and the reticular dermis. MAC-387 showed membrane staining in the viable epidermis ( Fig. 8). LMP-1 and EBNA2 for EBV were negative within the lymphoid cells as well as within the overlying epidermis. Figure 4. Immunohistochemical ,staining for CD3 showing diffuse staining of lymphoid cells within the epidermis and dermis (150×) Figure 5. Immunohistochemical ,staining for CD30 showing membrane and paranuclear staining of large atypical lymphoid cells within the epidermis and papillary dermis (a, 150× b, 400×) Figure 6. Immunohistochemical ,staining for S-100 protein within the epidermis and in the papillary dermis (a, 150× b, 300×) Figure 7. Immunohistochemical ,granular staining of large atypical lymphoid cells for TIA (200×) Figure 8. Immunohistochemical ,staining for MAC-387 showing epidermal staining (100×) Gene rearrangement studies showed a ,-T-cell receptor gene rearrangement. The monoclonal band was detected with VJ1, VJ2, and D1J2 primer sets. The T-cell receptor , rearrangement assay has a sensitivity of 61% and a specificity of 94% for the detection of a monoclonal rearrangement in T-cell lymphomas for which amplifiable DNA can be recovered. Electron microscopy was performed on formalin-fixed material, positive-fixed with 2.5% phosphate-buffered glutaraldehyde and further with 1% osmium tetroxide by standard techniques. Intracellular, 50,60-nm, cytoplasmic, spherical, viral-like particles were identified ( Fig. 9). Figure 9. Electron ,microscopy showing 50,60-nm diameter, intracellular, viral-like particles (arrows) (70,000×) [source] Microinjected neutrophils retain the ability to take up bacteriaJOURNAL OF ANATOMY, Issue 5 2002M. M. Bird It is now possible to microinject protein to probe specific biochemical pathways and/or cell functions in small cells such as human neutrophils (Bird et al. J.Anat.198, 2001). We have shown that these cells retain their ability to modify their F-actin cytoskeleton following the microinjection procedure. The principal task of neutrophils is to hunt and kill bacteria by responding to chemotactic gradients which cause them to extend actin rich pseudopodia in the direction of the highest concentration of these molecules. On reaching their target the neutrophils make tight contact with the bacteria and phagocytosis ensues. Here we address the question of whether or not the microinjected cells are still able to maintain their normal phagocytic activities. Human neutrophils maintained in culture for 20 mins were confronted with Staphylococcus aureus (1 × 104 cells/mL) for 5 min and then injected with rat IgG as an exogenous protein that also serves as a marker for injected cells. After 30 min the cells were fixed for fluorescence or confocal microscopy in 3.7% formaldehyde and permeabilised for 5 min (0.2% Triton X-100 in PBS). They were then incubated for 45 min in 2.5 µL FITC-anti rat IgG and 1 µL TRITC-phalloidin (to show the F-actin cytoskeleton), in 996.5 µL of PBS, washed 6 times in PBS and mounted on slides in 5 µL Mowiol containing a grain of antiquench. For TEM cells were fixed in 1.5% glutaraldehyde in cacodylate buffer for 3 min at room temperature and then washed in 0.2 m cacodylate buffer 6 times before incubation with 1 mm NiCl2 and SIGMA fast DAB peroxidase tablets for 30 min. The cells were postfixed in a 2% solution of osmium tetroxide for 30 min, dehydrated through a series of graded ethanols, and embedded and sectioned for TEM. By TEM the injected neutrophils were observed to have taken up bacteria into vacuoles of varying size. At the earliest stages of this process, prior to and immediately following the initial release of granular contents and the initiation of mechanisms to rapidly destroy bacteria, the bacteria fitted more tightly in the vacuoles than at later stages. Injected neutrophils commonly contained several bacteria; more than one bacterium was frequently located within a single vacuole of substantial size. Confocal laser microscopic observations confirmed that cells containing ingested bacteria also contained IgG. Thus injected cells not only survive the microinjection procedure but also retain their ability to take up bacteria and initiate the digestive process. [source] Intrinsic and acquired resistance to quaternary ammonium compounds in food-related Pseudomonas spp.JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003S. Langsrud Abstract Aims: To determine the sensitivity of a strain used for disinfectants testing (Pseudomonas aeruginosa ATCC 15442) and food-associated isolates to benzalkonium chloride and didecyl dimethylammonium chloride (DDAC). To determine whether the increase in bacterial resistance after adaptation to DDAC can be associated with phenotypic changes. To test the activity of alternative disinfectants to eliminate resistant Pseudomonas spp. Methods and Results:Pseudomonas aeruginosa ATCC 15442 was among the most resistant strains tested using a bactericidal suspension test. Growth of a sensitive Ps. fluorescens in gradually higher concentrations of DDAC resulted in stable higher resistance and to some cross-resistance to several antibacterial agents, with the exception of disinfectants containing chloramine T, glutaraldehyde or peracetic acid. It was shown by microscopy that adaptation was followed by loss of flagella, and slime formation. Removal of the slime by sodium dodecyl sulphate resulted in partial loss of the acquired resistance. Conclusions:Pseudomonas spp. may adapt to survive against higher concentrations of quaternary ammonium compounds (QACs), but resistant strains can be eliminated with chemically unrelated disinfectants. Significance and Impact of the Study: The work supports the rotation of disinfectants in food processing environments for avoiding the development of bacterial resistance to QACs. The alternating disinfectants should be chosen carefully, because of possible cross-resistance. [source] Possible mechanisms for the relative efficacies of ortho -phthalaldehyde and glutaraldehyde against glutaraldehyde-resistant Mycobacterium chelonaeJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2001S.E. Walsh Aims: This investigation compared glutaraldehyde (GTA)-sensitive and -resistant strains of Mycobacterium chelonae and examined the effects of pretreatment of GTA-sensitive and -resistant strains of Myco. chelonae with chemical agents that interfere with cell wall synthesis. Methods and Results: When exposed to 2% (v/v) GTA at 25°C, GTA-resistant strains of Myco. chelonae dried on to glass carriers were not inactivated to any significant extent. By contrast, GTA-sensitive strains of Myco. chelonae and a strain of Myco. terrae suffered a > 6 log reduction in viability in 5 min. However, ortho -phthalaldehyde (OPA; 0·5% w/v) achieved a corresponding inactivation against two GTA-resistant strains within 5,10 and 10,20 min, respectively. Electron microscopy, using a non-aldehyde fixation process and also negative staining, failed to detect any extensive changes in GTA-sensitive and -resistant cultures exposed to GTA or OPA. Thin-layer chromatography was unsuccessful in detecting differences between GTA-resistant and -sensitive strains of Myco. chelonae. However, pretreatment of GTA-resistant cells with mycobacterial cell wall synthesis inhibitors increased their subsequent susceptibility further to OPA but not to GTA. Conclusions:Ortho -phthalaldehyde is an effective new biocidal agent that, at its in-use concentration, is rapidly bactericidal to non-sporulating bacteria, including GTA-sensitive and -resistant mycobacteria. Significance and Impact of the Study: Pretreatment of GTA-resistant cells with mycobacterial cell wall synthesis inhibitors increased their subsequent susceptibility to OPA but not to GTA. [source] Synthesis and characterization of zwitterionic organogels based on Schiff base chemistryJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Nazia Tarannum Abstract Poly(sulfobetaine)s and poly(carboxybetaine)s have been extensively studied for their zwitterionic and biocompatible nature. The specific features that make such zwitterionic structures technologically important are their chemical structure, a straight forward synthetic route, high ionic contents with interesting dilute solution, and solid state properties. The objective of this work is to synthesize novel zwitterionic polymers having gel characteristics. Here, p- phenylene diamine/melamine react as nucleophiles with glutaraldehyde to produce poly(schiff base)s. In the subsequent step, the poly(sulfobetaine)s and poly(carboxybetaine)s were produced on treatment with 1,3-propane sultone/,-butyrolactone. Hence, a catalyst free facile approach to novel zwitterionic polymers was obtained. The polymers were characterized by elemental analyses, FTIR, XRD analyses, SEM, pH metric titrations, conductometric titrations, and thermal analyses (TGA/DTA). The polymeric samples carry the gel characteristics, showing lamellar structure with porous network. XRD pattern shows Bragg peaks indicative of superstructures. Thermal analysis indicates the Hoffman elimination of , hydrogen and subsequent release of sulfopropyl/carboxybutyl group. One of the gel polymers shows fluorescence also. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Controlled size chitosan nanoparticles as an efficient, biocompatible oligonucleotides delivery systemJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Romila Manchanda Abstract Polymeric nanoparticles of chitosan crosslinked with glutaraldehyde have been prepared using reverse micellar system. An optically clear solution was obtained on redispersing these nanoparticles in aqueous buffer. The nanoparticles were characterized for their size and surface morphology employing dynamic laser scattering (DLS) and transmission electron microscopy (TEM). The TEM images showed spherical particles with smooth surface and narrow size distribution of about 90 nm, which was also supported by DLS data. Size and morphology of the particles remains the same on redispersing the lyophilized powder of these nanoparticles in aqueous buffer. Further, these nanoparticles were loaded with different synthetic oligonucleotides (ODNs). In vitro pH dependent release of the adsorbed oligonucleotides from these nanoparticles was also studied. At basic pH the release of oligonucleotides was found higher as compared with neutral and acidic medium. Cytotoxicity studies done on HEK 293 cells reveals that oligonucleotide loaded nanoparticles have high cell viability of nearly 76,88% whereas those of lipofectamine was about 35%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Poly(vinyl alcohol),polyacrylamide blends with cesium salts of heteropolyacid as a polymer electrolyte for direct methanol fuel cell applicationsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010M. Helen Abstract A class of inorganic,organic hybrid membranes with low methanol permeability characteristics for possible direct methanol fuel cell (DMFC) applications was architected, formulated, and fabricated through the blending of poly(vinyl alcohol) (PVA) and polyacrylamide (PAM) followed by crosslinking with glutaraldehyde (Glu). Cesium salts of different heteropolyacids, including phosphomolybdic acid (PMA), phosphotungstic acid (PWA), and silicotungstic acid (SWA), were incorporated into the polymer network to form corresponding hybrid membrane materials, namely, PVA,PAM,CsPMA,Glu, PVA,PAM,CsPWA,Glu, and PVA,PAM,CsSWA,Glu, respectively (where "Cs" together with a heteropolyacid abbreviation indicates the cesium salt of that acid). All the three hybrid polymer membranes fabricated exhibited excellent swelling, thermal, oxidative, and additive stability properties with desired proton conductivities in the range 10,2 S/cm at 50% relative humidity. A dense network formation was achieved through the blending of PVA and PAM and by crosslinking with Glu, which led to an order of magnitude decrease in the methanol permeability compared to the state-of-the-art commercial Nafion 115 membrane. The hybrid membrane containing CsSWA exhibited a very low methanol permeability (1.4 × 10,8 cm2/s) compared to other membranes containing cesium salt of heteropolyacids such as PMA and PWA. The feasibility of these hybrid membranes as proton-conducting electrolytes in DMFC was investigated, and the preliminary results were compared with those of Nafion 115. The results illustrate the attractive features and suitability of the fabricated hybrid membranes as an electrolyte for DMFC applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polysaccharide-based artificial extracellular matrix: Preparation and characterization of three-dimensional, macroporous chitosan, and heparin composite scaffoldJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Shu-Huei Yu Abstract Scaffold-guided tissue engineering based on synthetic and natural occurring polymers has gained many interests in recent year. In this study, the development of a chitosan-heparin artificial extracellular matrix (AECM) is reported. Three-dimensional, macroporous composite AECMs composed of heparin (Hep) and chitosan (Chito) were prepared by an interpolyelectrolyte complex/lyophilization method. The Chito-Hep composite AECMs were, respectively, crosslinked with glutaraldehyde, as well as cocrosslinked with N,N -(3-dimethylaminopropyl)- N,-ethyl carbodiimide (EDC/NHS) and N -hydroxysuccinimide (NHS). The crosslinking reactions were examined by FT-IR analysis. In physiological buffer solution (PBS), the EDC/NHS-crosslinked Chito-Hep composite AECM showed a relative lower water retention ratio than its glutaraldehyde-crosslinked counterparts. The EDC/NHS-crosslinked Chito-Hep composite AECMs showed excellent biocompatibility, according to the results of the in vitro cytotoxic test. This result suggested that the EDC/NHS-crosslinked Chito-Hep composite AECMs might be a potential biomaterial for scaffold-guided tissue engineering applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Novel thermally and mechanically stable hydrogel for enzyme immobilization of penicillin G acylase via covalent techniqueJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Magdy M. M. Elnashar Abstract ,-Carrageenan hydrogel crosslinked with protonated polyethyleneimine (PEI+) and glutaraldehyde (GA) was prepared and evaluated as a novel biocatalytic support for covalent immobilization of penicillin G acylase (PGA). The method of modification of the carrageenan biopolymer is clearly illustrated using a schematic diagram and was verified by FTIR, elemental analysis, DSC, and INSTRON using the compression mode. Results showed that the gels' mechanical strength was greatly enhanced from 3.9 kg/cm2 to 16.8 kg/cm2 with an outstanding improvement in the gels thermal stability. It was proven that, the control gels were completely dissolved at 35°C, whereas the modified gels remained intact at 90°C. The DSC thermogram revealed a shift in the endothermic band of water from 62 to 93°C showing more gel-crosslinking. FTIR revealed the presence of the new functionality, aldehydic carbonyl group, at 1710 cm,1 for covalent PGA immobilization. PGA was successfully immobilized as a model industrial enzyme retaining 71% of its activity. The enzyme loading increased from 2.2 U/g (control gel) to 10 U/g using the covalent technique. The operational stability showed no loss of activity after 20 cycles. The present support could be a good candidate for the immobilization of industrial enzymes rich in amino groups, especially the thermophilic ones. © 2008 Wiley Periodicals, Inc. 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