Blend membranes from carboxymethylated chitosan/alginate in aqueous solution

The blend membranes were satisfactorily prepared by coagulating a mixture of O‐carboxymethylated chitosan (CM‐chitosan) and alginate in aqueous solution with 5 wt % CaCl₂, and then by treating with 1 wt % HCl aqueous solution. Their structure and miscibility were characterized by scanning electron micrograph, X‐ray diffraction, infrared spectra, differential thermal analysis, and atomic absorption spectrophotometer. The results indicated that the blends were miscible, when the weight ratio of CM‐chitosan to alginate was in the range from 1 : 1 to 1 : 5. The polymers interpenetration including a Ca²⁺ crosslinked bridge occurred in the blend membrane, and leads to high separation factor for pervaporation separation of alcohol/water and low permeation. The tensile strength in the wet state (σ_b = 192 kg cm⁻² for CM‐chitosan/alginate 1 : 1) and thermostability of the blend membranes were significantly superior to that of alginic acid membrane, and cellulose/alginate blend membranes, owing to a strong electrostatic interaction caused by —NH₂ groups of CM‐chitosan with —COOH groups of algic acid. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 610–616, 2000     

Preparation and Properties of Drug-Loaded Chitosan-Sodium Alginate Complex Membrane

Chitosan, sodium alginate and berberine complex membranes were prepared. The structure and properties of the drug-loaded membrane were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric and differential thermal analysis (DTA). The drug-release property of membranes with different ratios of chitosan and sodium alginate was also investigated. The results show that when chitosan and sodium alginate were mixed in weight ratio of 5:1, a polyelectrolyte complex film was formed and exhibited better thermal stability and stronger control ability over drug release.     

Preparation and evaluation of alginate/chitosan microspheres containing pheromones for pest control of Megaplatypus mutatus Chapuis (Platypodinae: Platypodidae)

This work describes the optimization of an alginate/chitosan microsphere preparation for the encapsulation of a sexual pheromone, 6‐methyl‐5‐hepten‐2‐ol (sulcatol), to realize a slow‐release device for the biological control of the Megaplatypus mutatus pest. To evaluate and select the best encapsulation/release conditions three parameters were studied: alginate concentration, pH of gelling solution and Ca²⁺/COO^? ratio. The preparation was optimized using biopolymers with improved mechanical properties and swelling behavior. The obtained microspheres were characterized using Fourier transform infrared spectroscopy, scanning electron and optical microscopies, swelling degree, mechanical properties and in vitro release of encapsulated pheromone. The microspheres performed best when they were synthesized using an alginate concentration of 4% w/v, at pH = 9 and with a Ca²⁺/COO^? ratio of 3.5. The attractiveness of the alginate/chitosan microspheres towards M. mutatus was demonstrated by behavioral bioassay with the completed pheromonal blend of the species (sulcatol, sulcatone and 3‐pentanol). The formulation can be considered as an efficient slow‐release biological control system, with no negative environmental impact. © 2015 Society of Chemical Industry     

单宁酸对海藻酸钠/壳聚糖微球性能的影响

研究了单宁酸的引入对海藻酸钠/壳聚糖水凝胶在微球化和微胶囊化应用性能方面的影响.首先制备了单宁酸交联改性的海藻酸钠/壳聚糖水凝胶微球.利用傅里叶变换红外光谱分析了共混物分子结构间的相互作用,采用热重分析仪考察了微球热稳定性,并研究了单宁酸的加入对微球粒径、含水量和溶胀性的影响.结果表明由于单宁酸与海藻酸钠/壳聚糖之间的...     

Preparation and characterization of ciprofloxacin‐loaded alginate/chitosan sponge as a wound dressing material

The aim of this study is preparation and characterization of alginate/chitosan sponges including a model antibiotic (i.e., ciprofloxacin) to use in wound and/or burn treatment. Sponges were prepared firstly by the gelation of sodium alginate followed by lyophilization, crosslinking with calcium chloride, and finally coating with chitosan. Sponges were characterized with respect to morphology, water uptake, in vitro drug release behavior, and antimicrobial activity. Investigated and evaluated parameters in all of these studies were selected as the concentration of calcium chloride, alginate viscosity, drug content, and molecular weight of chitosan. Drug release and water uptake were found to be greatly influenced by these parameters. Water uptake and drug release rate were decreased by increasing the crosslinking density, chitosan molecular weight, and alginate viscosity. In the antimicrobial tests, it was obtained that the antimicrobial activity is directly proportional with the release rates and water uptake. Morphological studies showed a highly porous structure with interconnected pores. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1602–1609, 2006     

Adsorption of lanthanum by magnetic alginate‐chitosan gel beads

BACKGROUND: The risk of environmental pollution is aggravated by the increasing application of considerable amounts of rare earth elements in advanced materials. This paper reports the preparation of novel magnetic alginate–chitosan gel beads and their application for adsorption of lanthanum ions from aqueous solution. RESULTS: Stable magnetic alginate–chitosan gel beads with average diameter 0.85 ± 0.05 mm were prepared by loading iron oxide nanoparticles onto a combined alginate and chitosan absorbent. The performance of the prepared beads for the adsorption of lanthanum ions from aqueous solution was tested. It was found that various parameters, such as aqueous pH, contact time, metal ion concentration, ion strength and temperature, have an effect on the adsorption. Adsorption equilibrium was reached in 10 h and the maximum uptake capacity was 97.1 mg g^?1. From the analysis of pH, FTIR and XPS data, it is proposed that lanthanum adsorption proceeds through mechanisms of cation exchange, electrostatic interaction and surface complexation, with the oxygen atoms the main binding sites. In addition, lanthanum ions could be selectively separated from coexisting base metal ions such as Pb (II), Cd (II), Co (II), Ni (II) and Cu (II) in the aqueous solution. CONCLUSION: The prepared magnetic alginate–chitosan gel beads exhibit high uptake capacity and selectivity for lanthanum sorption, and thus can be used for adsorptive recovery of lanthanum from aqueous solutions. Copyright © 2010 Society of Chemical Industry     

Beta cyclodextrin–insulin‐encapsulated chitosan/alginate matrix: Oral delivery system

Cyclodextrins (CD) form inclusion complexes with many drug molecules. The complexed drugs have increased bioabsorption in in vivo system. We have attempted to complex insulin with β‐Cyclodextrin (BCD) and encapsulate in the chitosan/calcium alginate matrix. For drug release studies insulin complexed with BCD for 20 min and that complexed with BCD for 150 min have been used for encapsulation in the chitosan/calcium alginate matrix. The two matrices seem to have different drug release profiles in simulated intestinal medium (pH 7.4) It appears that drug release from the 20‐min BCD complexed system encapsulated in the chitosan/calcium alginate matrix begins only after an hour, where, being released from the 150‐min BCD complexed system it begins in the first hour itself. Also, aggregation of the insulin molecules seems to be reduced by the complexation of the drug with BCD. Another noticeable fact is the change in the loading character, which is found to be inversely related to the concentration of BCD when it is above the stoichiometric equivalent of the drug. In an attempt to increase the payload of the drug in the matrix, the pH of the processing medium consisting of calcium chloride and chitosan is varied. It is found that the encapsulation efficiency increases as the pH is decreased from 6.0 to 4.0. Another way of increasing the loading is studied by decreasing the concentration gradient of insulin in the processing alginate solution and the crosslinking medium consisting of chitosan/calcium chloride. Preliminary animal studies on rabbits seem to be promising. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1089–1096, 2000     

Viscoelastic sol–gel state of the chitosan and alginate solution mixture

The rheological behavior of chitosan/alginate solutions was investigated in relation to gelation and polyelectrolyte complex (PEC) formation. Before mixing, the chitosan and the alginate solutions were both homogeneous fluids. However, heterogeneity developed after mixing, accompanied by a serious increase of viscosity. To determine the sol–gel state of the solutions, the viscoelastic variables, such as the dynamic storage modulus (G′) and loss modulus (G″), the loss tangent, and the viscoelastic exponents for G′ and G″, were obtained. Depending on the concentration, the chitosan/alginate solutions revealed unexpected rheological behavior. At a polymer concentration of 1.0 wt %, the chitosan/alginate solution was in a viscoelastic gel state, whereas, at higher concentrations, viscoelastic sol properties were dominant. A viscoelastic gel state for the chitosan/alginate solution was induced based on the weak formation of fiber‐shaped precipitates of a PEC at a low polymer concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1408–1414, 2007     

Optimization of lactic acid production from whey by L casei NRRL B‐441 immobilized in chitosan stabilized Ca‐alginate beads

The production of lactic acid from whey by Lactobacillus casei NRRL B‐441 immobilized in chitosan‐stabilized Ca‐alginate beads was investigated. Higher lactic acid production and lower cell leakage were observed with alginate–chitosan beads compared with Ca‐alginate beads. The highest lactic acid concentration (131.2 g dm^?3) was obtained with cells entrapped in 1.3–1.7 mm alginate–chitosan beads prepared from 2% (w/v) Na‐alginate. The gel beads produced lactic acid for five consecutive batch fermentations without marked activity loss and deformation. Response surface methodology was used to investigate the effects of three fermentation parameters (initial sugar, yeast extract and calcium carbonate concentrations) on the concentration of lactic acid. Results of the statistical analysis showed that the fit of the model was good in all cases. Initial sugar, yeast extract and calcium carbonate concentrations had a strong linear effect on lactic acid production. The maximum lactic acid concentration of 136.3 g dm^?3 was obtained at the optimum concentrations of process variables (initial sugar 147.35 g dm^?3, yeast extract 28.81 g dm^?3, CaCO₃ 97.55 g dm^?3). These values were obtained by fitting of the experimental data to the model equation. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in lactic acid production using alginate–chitosan‐immobilized cells. Copyright © 2005 Society of Chemical Industry     

Characterization of gamma irradiated concentrated aqueous solutions of chitosan/sodium alginate blends and their drug uptake‐release characters

Blends films based on different ratios of concentrated aqueous solutions of chitosan (CS) and sodium alginate (AG) in the presence of 1% of glutaraldehyde, as a cross‐linking agent for chitosan, were prepared by solution casting and then exposed to gamma irradiation. The formed blends were characterized by IR spectroscopic analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The uptake‐release properties of CS/AG blends, taking ketoprofen as an example for drug, were also investigated. DSC thermograms of CS/AG blends revealed good miscibility was sustained between CS and AG. The water uptake and gel content of CS/AG blends was found to decrease by increasing the ratio of AG in the initial solution. The IR spectra indicated the formation of cross‐linking and hydrogen bonding, while the TGA study showed that the CS/AG blends displayed higher thermal stability than pure CS polymer. Based on Fick's law, it was demonstrated that the main parameters affecting the release of ketoprofen drug from the CS/AG blend hydrogels were composition and pH. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polyelectrolyte complexes of sodium alginate with chitosan or its derivatives for microcapsules

Chitosan, a cationic polysaccharide, was heterogeneously deacetylated with a 47% sodium hydroxide solution and followed by a homogeneous reacetylation with acetic anhydrides to control the N-acetyl content of the chitosan having a similar molecular weight. The chitosans having different degrees of N-acetylation were complexed with sodium alginate, an anionic polysaccharide, and the formation behavior of polyelectrolyte complexes (PECs) was examined by the viscometry in various pH ranges. The maximum mixing ratio (R_max) increased with a decrease in the degree of N-acetylation of the chitosan at the same pH, and with a decrease in pH at the same degree of N-acetylation. Similarly, N-acylated chitosans were also prepared. The N-acyl chitosans scarcely affected the formation behavior of PECs with sodium alginates. For the application of the PECs produced, the microencapsulation of a drug was performed and the release property of drug was tested. The microcapsules were prepared in one step by the extrusion of a solution of guaifenesin and sodium alginate into a solution containing calcium chloride and chitosan through interpolymeric ionic interactions. The drug release during the drug-loaded microcapsules storage in saline was found to depend on the pH where the microcapsules were formed and the kind of N-acyl groups introduced to the chitosan. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 425–432, 1997     

海藻酸盐/壳聚糖复合微球的制备及其控制释放作用

采用喷雾干燥法将活性成分包载到海藻酸钠微凝胶中,再经钙离子和壳聚糖交联得到复合微球。以维生素B₂为模型药物探讨了微球的控制释放效果和机理。扫描电镜分析表明海藻酸钠微凝胶经复合交联后形成了团聚体结构。与单一钙离子交联的海藻酸盐微球相比,复合微球对维生素B₂释放更慢,半数释放时间(t₅₀)延长约6倍,且交联时间越长、交联剂用量越高,维生素B₂释放越慢。当载药量介于16.0%～35.6%时,维生素B₂释放时间达24 h以上,释放过程主要受费克扩散控制。     

Oxygen diffusivity in alginate/chitosan microcapsules

BACKGROUND: Oxygen diffusion properties affect the proliferation and metabolism of cells cultured in microcapsules with a polyelectrolyte complex membrane. The effective diffusion coefficient (De) of oxygen in alginate/chitosan (AC) microcapsules under different preparation conditions was calculated, and a mathematic model was developed to investigate the effect of oxygen diffusion on cell loading in the microcapsules. RESULTS: Oxygen De in AC microcapsules was independent of alginate solution concentration, intrinsic viscosity of alginate and different polyelectrolyte complex membranes. De decreased from 2.1 ± 0.3 × 10^?9 to 0.17 ± 0.01 × 10^?9 m² s^?1 as microcapsule diameter decreased from 1800 to 45 0 µm. Microcapsule density was increased from 1.013 ± 0.000 to 1.034 ± 0.003 g mL^?1 as diameter decreased from 1775 to 430 µm. The mathematic model results showed that critical CHO cell loadings were 1.8 × 10⁸ or 1.1 × 10⁸ cells mL^?1 in microcapsules with 450 or 1800 µm diameter, respectively. CONCLUSIONS: No significant difference was found of oxygen De between calcium alginate beads and AC microcapsules. The decrease of De with diameter was attributed to the increasing density and compact degree on the surface. The model results indicated that risk on necrosis rose with the increasing diameter. Microcapsules with smaller diameters may have more advantages on cell culture. © 2012 Society of Chemical Industry     

重组人粒细胞-巨噬细胞集落刺激因子壳聚糖-海藻酸钠微囊的制备

目的以壳聚糖和海藻酸钠为原料,制备重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)微囊,探讨开发口服蛋白多肽类药物的可行性。方法以rhGM-CSF为药物模型,通过壳聚糖与海藻酸钠聚电解质的络合反应制备rhGM-CSF壳聚糖-海藻酸钠微囊,观察微囊的形态大小,测定其包封率,不同pH值下的膨胀度和体外释放率。结果制备的rhGM-CSF壳聚糖-海藻酸钠微囊呈均匀、完整的圆球形,平均直径1mm左右;包封率达80%以上;在模拟肠液(磷酸盐缓冲液,pH7.4)中浸泡3h,膨胀度可达600%,药物释放率达85%以上。结论壳聚糖-海藻酸钠微囊具有肠溶控释作用,有望成为rhGM-CSF等蛋白类口服药物的控释载体。     

Poly(L‐histidine)‐chitosan/alginate complex microcapsule as a novel drug delivery agent

Novel poly(L ‐histidine)‐chitosan/alginate complex microcapsules were prepared from biodegradable polymers poly(L ‐histidine) (PLHis) in the presence of chitosan at acetate buffer solution pH 4.6. Microcapsules obtained are spherical and well‐dispersed with a smooth surface and a narrow size distribution. The microcapsules can encapsulate the protein model drug hemoglobin (Hb) efficiently. The results show that the complex microcapsules with low, medium, or high molecular weight of chitosan (0.05%, w/v), the highest encapsulation efficiencies obtained are 91.3%, 85.9%, and 94.2% with loading efficiencies of 47.8%, 44.3%, and 39.7%, respectively. The release profiles indicate that Hb‐loaded microcapsules conform to first‐order release kinetic in whole procedure, and 84.8%, 71.4%, and 87.3% of Hb were released during 72‐h incubation in PBS pH6.8 for microcapsules with low, medium, and high molecular weight chitosan (0.05%, w/v), respectively. The results also indicate that particle size and drug loading efficiency have a significant influence on the release profile and encapsulation efficiency. Our results reveal that the PLHis‐chitosan/alginate complex microcapsules are able to encapsulate and release Hb and are potential carriers for protein drugs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polyelectrolyte complex beads composed of water‐soluble chitosan/alginate: Characterization and their protein release behavior

Polyelectrolyte complex (PEC) beads were prepared from water‐soluble chitosan (WSC) and alginate complex solution with different ratios by dropping method, and all procedures used were performed in aqueous medium at neutral environment. The structure and morphology of the beads were characterized by IR spectroscopy and scanning electron microscopy (SEM). IR spectroscopy confirmed the electrostatic interactions between amino groups of WSC and carboxyl groups of alginate. SEM showed internal section of the PEC bead, which had porous structure compared with compact structure of alginate beads. The swelling behavior, encapsulation efficiency, and release behavior of bovine serum albumin (BSA) from the beads at different pHs were investigated. PEC beads demonstrated different responses to pH from alginate beads. The ratio of WSC to alginate influenced the encapsulation and release of BSA. At pH 1.2, small amount (< 15%) of BSA was released from the PEC beads except AC12. However, at pH 7.4, a large amount (> 80%) of BSA was released from AL in the first 3 h due to the rapid disintegration of the beads, whereas BSA release was retarded from complex beads due to the forming of PEC. The results suggested that the WSC/alginate beads could be a suitable polymeric carrier for site‐specific protein drug delivery in the intestine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4614–4622, 2006     

Chitosan/polyethylene glycol–alginate microcapsules for oral delivery of hirudin

A mild chitosan/calcium alginate microencapsulation process, as applied to encapsulation of biological macromolecules such as albumin and hirudin, was investigated. The polysaccharide chitosan was reacted with sodium alginate in the presence of calcium chloride to form microcapsules with a polyelectrolyte complex membrane. Hirudin-entrapped alginate beads were further surface coated with polyethylene glycol (PEG) via glutaraldehyde functionalities. It was observed that approximately 70% of the content is being released into Tris-HCl buffer, pH 7.4 within the initial 6 h and about 35% release of hirudin was also observed during treatment with 0.1 M HCl, pH 1.2 for 4 h. But acid-treated capsules had released almost all the entrapped hirudin into Tris-HCl, pH 7.4 media within 6 h. From scanning electron microscopic and swelling studies, it appears that the chitosan and PEG have modified the alginate microcapsules and subsequently the protein release. The microcapsules were also prepared by adding dropwise albumin-containing sodium alginate mixture into a PEG– CaCl₂ system. Increasing the PEG concentration resulted in a decrease rate of albumin release. The results indicate the possibility of modifying the formulation to obtain the desired controlled release of bioactive peptides (hirudin), for a convenient gastrointestinal tract delivery system. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2143–2153, 1998     

海藻酸钠/壳聚糖微囊的研究进展

海藻酸钠(sodium alginate,SA)是从褐藻或海藻中提取出来的聚阴离子电解质;壳聚糖(chitosan,CS)是通过甲壳素脱乙酰化获得的聚阳离子电解质。这两种物质都具有优异的生物相容性、良好的生物可降解性、抗菌性和伤口愈合活性。介绍了海藻酸钠/壳聚糖微囊的生物特性,制备方法及其在医学领域中的应用,并对其应用前景进行展望。     

Removal of Hg2+ from aqueous solution using a novel composite carbon adsorbent

A novel composite carbon adsorbent (GCA) has been prepared by immobilizing activated carbon and genipin‐crosslinked chitosan into calcium alginate gel beads via entrapment and applied to the removal of mercury (Hg²⁺) ions from aqueous solution (e.g., drinking water). Two bead sizes and two mixing ratios of components were obtained and characterized. Batch experiments were performed to study the uptake equilibrium and kinetics of Hg²⁺ ions by the GCA. The Hg²⁺ adsorption capacity of GCA was found to be dependent of pH and independent of size of the adsorbent. The Hg²⁺ adsorption rate of GCA increases with decreasing its bead size. However, both adsorption capacity and rate of GCA for Hg²⁺ increase with increasing its chitosan content. Otherwise, it was shown that the GCA has higher Hg²⁺ adsorption capacity and rate than activated carbon, which might be caused by the incorporation of chitosan into the GCA. The maximum Hg²⁺ adsorption capacity of GCA was found to be 576 mg/g, which is over seven times higher than that of activated carbon. Our results reveal the uniform distribution of activated carbon and chitosan within the alginate gel bead and that Hg²⁺ ions can diffuse inside the bead. It also demonstrated the feasibility of using this GCA for Hg²⁺ removal at low pH values. The Hg²⁺ absorbed beads of the GCA can be effectively regenerated and reused using H₂SO₄. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

金银花水饮料澄清工艺研究

采用单一壳聚糖澄清处理金银花浸提液,通过正交试验研究确定最佳澄清工艺条件;在最佳工艺基础上,初步研究壳聚糖/海藻酸钠复合絮凝剂对金银花浸提液的澄清效果。研究结果表明,絮体加固剂海藻酸钠的加入有利于提高浸提液的有效成分,且可以获得较好的澄清效果。