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Chitosan Solution (chitosan + solution)
Selected AbstractsSTEADY-SHEAR RHEOLOGY OF CONCENTRATED CHITOSAN SOLUTIONSJOURNAL OF TEXTURE STUDIES, Issue 1 2004A. MARTÍNEZ ABSTRACT i [source] Preparation of tofu using chitosan as a coagulant for improved shelf-lifeINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2004Hong Kyoon No Summary The potential of chitosan as a coagulant in commercial tofu preparation was investigated with six chitosans of different molecular weights using various treatments. The following optimum processing conditions for tofu preparation were proposed: chitosan with a molecular weight of 28 kDa; chitosan solution type, 1% chitosan/1% acetic acid; chitosan solution to soymilk ratio, 1 : 8; coagulation temperature, 80 °C; coagulation time, 15 min. However, the sensory quality of tofu was notably improved using a 1 : 1 mixture of 1% acetic acid and 1% lactic acid instead of 1% acetic acid alone as a chitosan solvent. Tofu prepared with chitosan had lower ash and higher protein content than those of commercial products tested. In storage tests, the chitosan-tofu had a longer shelf-life, about 3 days, than tofu made with CaCl2. This added shelf-life is significant in view of the magnitude (366 000 tonnes year,1) of tofu produced from commercial tofu plants (1407 plants as of 1998) in Korea. [source] Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatmentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Min Lang Tsai Abstract The objective of this study was to propose a facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration (UF) treatment. The proposed method was based on the degradation rate and rate constant of various process variables, such as: solution temperature, reaction time, concentration of chitosan solution, with or without concurrent removal of degraded fragments during mechanical shearing. The result obtained was that the degradation rate constant was 1.8,6.0 times higher for those using UF to remove smaller degraded molecules concurrently during treatment, than that without UF treatment. The degradation rate constant increased with increasing solution temperature; however, the solution temperature should not exceed than 50°C to prevent the undesired color changes of the resulting product. A method combining mechanical shearing/UF treatment at 50°C and ultrasonic radiation or microfluidization/UF treatment at 30°C is proposed here for a facile method to manipulate the molecular weight of the resultant chitosan with an energy saving, efficient and practical mass production. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Application of chitosan solutions gelled by melB tyrosinase to water-resistant adhesivesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Kazunori Yamada Abstract An investigation was undertaken on the application of dilute chitosan solutions gelled by melB tyrosinase-catalyzed reaction with 3,4-dihydroxyphenethylamine (dopamine). The tyrosinase-catalyzed reaction with dopamine conferred water-resistant adhesive properties to the semi-dilute chitosan solutions. The viscosity of the chitosan solutions highly increased by the tyrosinase-catalyzed quinone conversion and the subsequent nonenzymatic reactions of o -quinones with amino groups of the chitosan chains. The viscosity of chitosan solutions highly increased in shorter reaction times by addition of melB tyrosinase. Therefore, in this study, the gelation of a chitosan solution was carried out without poly(ethylene glycol) (PEG), which was added for the gelation of chitosan solutions using mushroom tyrosinase. The highly viscous, gel-like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and were held under water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. An increase in either amino group concentration of the chitosan solutions or molecular mass of the chitosan samples used effectively led to an increase in adhesive strength of the glass slides. Adhesive strength obtained by chitosan materials gelled enzymatically was higher than that obtained by a chitosan gel prepared with glutaraldehyde as a chemical crosslinking agent. In addition, the use of melB tyrosinase led to a sharp increase in adhesive strength in shorter reaction times without other additives such as PEG. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Polyelectrolyte complex hydrogel composed of chitosan and poly(,-glutamic acid) for biological application: Preparation, physical properties, and cytocompatibilityJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Hahk-Soo Kang Abstract Polyelectrolyte complex (PEC) hydrogels composed of chitosan as a cationic polyelectrolyte and poly (,-glutamic acid) (,-PGA) as an anionic polyelectrolyte were prepared from PEC dispersions based on a chitosan solution to which different amounts of ,-PGA solutions were added to charge equivalency. The chemical structures of the PEC hydrogels were investigated by Fourier transform infrared spectroscopy. The physical properties, fixed charge concentration, crystallinity, mechanical properties, micromorphology, and swelling properties of the PEC hydrogels were also investigated. The total fixed charge concentration of the PEC hydrogels varied as a function of pH on the pK intervals between chitosan (pK = 6.5) and ,-PGA (pK = 2.27). The isoelectric points (IEP) were shifted to a lower pH with a higher weight ratio of ,-PGA to chitosan. The elastic modulus was decreased with the weight ratio increasing from 0 : 1 to 1 : 1 (,-PGA/chitosan) by ionic crosslinking between the amino groups of chitosan and the carboxyl groups of ,-PGA. The results of the swelling study showed that the swelling properties of PEC hydrogels were more affected by the change in the elastic restoring force than by the change in the fixed charge concentration depending on the pH. Also, the cytotoxicity of the PEC hydrogels was investigated using normal human dermal fibroblast (NHDF) cell lines, and the results showed the PEC hydrogels were not toxic. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:386,394, 2007 [source] Effects of chitosan solution concentration and incorporation of chitin and glycerol on dense chitosan membrane propertiesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007Paula Rulf Marreco Dallan Abstract The aim of this work was to perform a systematic study about the effects induced by chitosan solution concentration and by chitin or glycerol incorporation on dense chitosan membranes with potential use as burn dressings. The membrane properties analyzed were total raw material cost, thickness, morphology, swelling ratio, tensile strength, percentage of strain at break, crystallinity, in vitro enzymatic degradation with lysozyme, and in vitro Vero cells adhesion. While the use of the most concentrated chitosan solution (2.5% w/w) increased membrane cost, it also improved the biomaterial mechanical resistance and ductility, as well as reduced membrane degradation when exposed for 2 months to lysozyme. The remaining evaluated properties were not affected by initial chitosan solution concentration. Chitin incorporation, on the other hand, reduced the membranes cost, swelling ratio, mechanical properties, and crystallinity, resulting in thicker biomaterials with irregular surface more easily degradable when exposed to lysozyme. Glycerol incorporation also reduced the membranes cost and crystallinity and increased membranes degradability after exposure to lysozyme. Strong Vero cells adhesion was not observed in any of the tested membrane formulations. The overall results indicate that the majority of the prepared membranes meet the performance requirements of temporary nonbiodegradable burn dressings (e.g. adequate values of mechanical resistance and ductility, low values of in vitro cellular adhesion on their surfaces, low extent of degradation when exposed to lysozyme solution, and high stability in aqueous solutions). © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Effect of Plasticizer Concentration and Solvent Types on Shelf-life of Eggs Coated with ChitosanJOURNAL OF FOOD SCIENCE, Issue 4 2006Su Hyun Kim ABSTRACT:, Effects of plasticizer concentrations (0, 0.5, 1.0, 1.5, and 2.0% glycerol) and solvent types (1% acetic and 1% lactic acid) on internal quality of eggs coated with 2% chitosan solution were evaluated during 5 wk of storage at 25 °C. In comparison of plasticizer concentrations, eggs coated with chitosan dissolved in acetic acid containing 2% glycerol showed significant reduction in weight loss compared with the noncoated eggs during 5 wk of storage. At 2% glycerol, the Haugh unit and yolk index values suggested that chitosan-coated eggs can be preserved for at least 3 wk longer than the control noncoated eggs during 5 wk of storage at 25 °C. Use of acetic acid rather than lactic acid as a chitosan solvent was more advantageous in view of shelf-life extension of eggs. [source] Preparation of polylactide-co-glycolide and chitosan hybrid microcapsules of amifostine using coaxial ultrasonic atomizer with solvent evaporationJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2008Sarala Pamujula The objective of this study was to evaluate the effect of various processing and formulation factors on the characteristics of amifostine hybrid microcapsules. Amifostine-loaded hybrid microcapsules were prepared using PLGA and chitosan. In short, amifostine powder was dissolved in de-aerated water with or without chitosan. The amifostine solution was later emulsified into PLGA solution in dichloromethane containing phosphatidylcholine. The resultant emulsion was fed through the inner capillary of a coaxial ultrasonic atomizer. The liquid fed through the coaxial outer capillary was either water or chitosan solution. The atomized droplets were collected into PVA solution and the droplets formed microcapsules immediately. The hybrid microcapsules prepared with chitosan solution only as an outer layer liquid showed the maximum efficiency of encapsulation (30%). The median sizes of all three formulations were 33,44 ,m. These formulations with chitosan showed positive zeta-potential and sustained drug release with 13,45% amifostine released in 24 h. When chitosan was incorporated into inner as well as outer liquid layers, the drug release increased significantly, 45% (compared with other formulations) released in 24 h and almost 100% released in 11 days. Hybrid microcapsules of amifostine showed moderately high efficiency of encapsulation. The cationic charge (due to the presence of chitosan) of these particles is expected to favour oral absorption and thus overall bioavailability of orally administered amifostine. [source] Effect of chitosan on the intranasal absorption of salmon calcitonin in sheepJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2005Michael Hinchcliffe The effects of a chitosan-based delivery system on the pharmacokinetics of intranasally administered salmon calcitonin (sCT) were investigated in a sheep model. In particular, the feasibility of producing a formulation with a comparable or improved bioavailability and/or less variability than the currently marketed nasal product (Miacalcin nasal spray, Novartis Pharmaceuticals) was assessed. A comparator (control) formulation comprising sCT solution was also tested. Sheep (n = 6) were dosed intranasally according to a randomized crossover design. The intranasal sCT dose was 1100 IU (equivalent to approximately 17 IU kg,1). After completion of the nasal dosing legs, five of the sheep received 300 IU sCT (equivalent to approximately 5 IU kg,1) by subcutaneous injection to estimate relative bioavailability. After intranasal or subcutaneous dosing, serial blood samples were taken and plasma separated by centrifugation before measuring sCT concentrations by ELISA. Pharmacokinetic (non-compartmental) and statistical (analysis of variance or non-parametric alternative) analyses were performed. No systemic or local adverse effects were observed following intranasal or subcutaneous administration of sCT. The mean relative bioavailability of sCT from the chitosan solution was improved twofold compared with Miacalcin nasal spray and threefold compared with sCT control solution. Inter-animal variability in sCT absorption appeared to be lower with use of the chitosan-based solution compared with the control solution or commercial product. Based on the reported sheep data, a chitosan delivery system could offer the potential to significantly improve the intranasal absorption of sCT and reduce the variability in absorption. In the clinical setting, this may allow relatively lower doses of the drug to be given intranasally and/or lead to improvements in the efficacy or quality of intranasal therapy. [source] Straightforward Determination of the Degree of N -Acetylation of Chitosan by Means of First-Derivative UV SpectrophotometryMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 14 2008Ricardo M. P. da Silva Abstract First-derivative UV spectrophotometry is shown to be a reliable method for the determination of the degree of N- acetylation of chitosan samples. A mathematical expression is derived that allows to determine the DA directly from the mass concentration of a chitosan solution and the first derivative of its UV spectrum at 202 nm, thus eliminating the need for empiric correction curves for highly deacetylated samples. A procedure is proposed for the accurate mass determination of the hygroscopic chitosan. The proposed approach facilitates the routine determination of the DA, especially when using potent multiwell microplate readers, which allow hundreds of samples to be measured in just a few minutes. [source] Use of chitosan for removal of bisphenol A and bisphenol derivatives through tyrosinase-catalyzed quinone oxidationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010Mizuho Suzuki Abstract In this study, the availability of chitosan was systematically investigated for removal of bisphenol A (BPA, 2,2-bis(hydroxyphenyl)propane) through the tyrosinase-catalyzed quinone oxidation and subsequent quinone adsorption on chitosan beads. In particular, the process parameters, such as the hydrogen peroxide (H2O2)-to-BPA ratio, pH value, temperature, and tyrosinase dose, were discussed in detail for the enzymatic quinone oxidation. Tyrosinase-catalyzed quinone oxidation of BPA was effectively enhanced by adding H2O2 and the optimum conditions for BPA at 0.3 mM were determined to be pH 7.0 and 40°C in the presence of H2O2 at 0.3 mM ([H2O2]/[BPA] = 1.0). Removal of BPA from aqueous solutions was accomplished by adsorption of enzymatically generated quinone derivatives on chitosan beads. The use of chitosan in the form of beads was found to be more effective because heterogeneous removal of BPA with chitosan beads was much faster than homogeneous removal of BPA with chitosan solutions, and the removal efficiency was enhanced by increasing the amount of chitosan beads dispersed in the BPA solutions and BPA was completely removed by quinone adsorption in the presence of chitosan beads more than 0.10 cm3/cm3. In addition, a variety of bisphenol derivatives were completely or effectively removed by the procedure constructed in this study, although the enzyme dose or the amount of chitosan beads was further increased as necessary for some of the bisphenol derivatives used. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Application of chitosan solutions gelled by melB tyrosinase to water-resistant adhesivesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Kazunori Yamada Abstract An investigation was undertaken on the application of dilute chitosan solutions gelled by melB tyrosinase-catalyzed reaction with 3,4-dihydroxyphenethylamine (dopamine). The tyrosinase-catalyzed reaction with dopamine conferred water-resistant adhesive properties to the semi-dilute chitosan solutions. The viscosity of the chitosan solutions highly increased by the tyrosinase-catalyzed quinone conversion and the subsequent nonenzymatic reactions of o -quinones with amino groups of the chitosan chains. The viscosity of chitosan solutions highly increased in shorter reaction times by addition of melB tyrosinase. Therefore, in this study, the gelation of a chitosan solution was carried out without poly(ethylene glycol) (PEG), which was added for the gelation of chitosan solutions using mushroom tyrosinase. The highly viscous, gel-like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and were held under water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. An increase in either amino group concentration of the chitosan solutions or molecular mass of the chitosan samples used effectively led to an increase in adhesive strength of the glass slides. Adhesive strength obtained by chitosan materials gelled enzymatically was higher than that obtained by a chitosan gel prepared with glutaraldehyde as a chemical crosslinking agent. In addition, the use of melB tyrosinase led to a sharp increase in adhesive strength in shorter reaction times without other additives such as PEG. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] | |||||||||||||