海藻酸钠/壳聚糖微载体的研究进展

海藻酸钠(sodium alginate,SA)是从褐藻类中提取的一种具有生物活性、可生物降解的聚阴离子电解质;壳聚糖(chitosan,CS)是一种天然的、含有氨基的亲水性多糖,是一种聚阳离子电解质。SA/CS微载体是一种天然的高分子材料,具有无毒性、生物相容性、生物降解性,且能够与生物大分子药物结合,使其所载药物可缓慢且稳定地释放,从而实现药物的靶向作用,因此SA/CS微载体在生物医学领域具有广阔的应用前景。本文就SA/CS微载体的生物特性、制备方法、体外释放特性及其作为药物载体的相关应用作一综述。     

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。     

干扰素壳聚糖/海藻酸钠微囊控释制剂载体的初步研究

目的研究蛋白质类药物口服控释给药的可行性。方法壳聚糖与海藻酸钠通过聚电解质络合反应制备成壳聚糖/海藻酸钠微囊,以干扰素为模型药物,研究不同pH条件下,药物的控制释放情况。结果微囊的粒径为1 mm左右,其干扰素的包封率达90.0%以上,微囊在模拟胃液(pH1.0)中,3h药物释放不到5%;在模拟肠液(pH7.4)中,3h药物释放近100%。结论壳聚糖/海藻酸钠微囊有可能成为蛋白质类药物口服控释制剂的载体。     

壳聚糖/海藻酸钠/活性肽复合膜的制备与性能研究

以壳聚糖和海藻酸钠高分子为基质原料,采用层层自组装技术形成聚电解质复合多层膜,并包裹深海鱼蛋白活性肽,考察复合膜的厚度、溶胀度、透气性、抗拉伸强度、累积释放度等基本性能。结果表明,制备复合膜的最佳条件为壳聚糖(分子量50kDa)与海藻酸钠的质量分数比2∶1。在此条件下,制备复合膜层数为7层时,其厚度为0.041mm、透气性63.96%、溶胀度为179.92%,断裂拉伸率为12.45%,3h累计释放度为11.58%,显示出优越的生物医用膜性能,这将为开发一种新型的生物创伤医用膜提供参考。     

壳聚糖/海藻酸钙复合单丝的制备与性能研究

为解决聚电解质壳聚糖与海藻酸钠混合溶液相反电荷团聚,采用核壳喷丝头,将添加氯化钙的壳聚糖混合纺丝液和海藻酸钠纺丝液经喷丝头的壳层、核心分别喷出后,然后两种溶液之间发生缓慢的离子键络合,海藻酸钠在氯化钙作用下,缓慢变为海藻酸钙,并在重力作用下牵伸,得到结构均匀致密的复合单丝。通过对复合单丝结构、性能分析表明,2%壳聚糖溶液中氯化钙溶液添加量为壳聚糖溶液质量的7%,1.5%海藻酸钠溶液,复合单丝的强力达到1.14 cN/dtex,较未加入氯化钙的复合单丝提高了55.4%,在水中浸泡1 h后的溶胀比达到33.2,表明该复合单丝制作的敷料保水性能好,具有较好的应用前景。     

纳米缓释微胶囊的制备及其缓释性能

以海藻酸钠、壳聚糖、啶虫脒为原料,采用高压静电喷雾法制备了纳米海藻酸钠/壳聚糖微胶囊,并采用紫外分光光度计研究了其释药行为。结果表明:纳米海藻酸钠/壳聚糖微胶囊能够实现药物缓释作用,且药物释放比例高达90%。从纳米海藻酸钠/壳聚糖微胶囊释药表现发现其药物释放规律:当波长为250 nm时,吸光度(y)和浓度(x)的定量计算关系为y=0.095 2x-0.000 6,为进一步研究纳米海藻酸钠/壳聚糖微胶囊释药能力的提升奠定了基础。     

海藻酸钠-壳聚糖复合膜中溶氧扩散性能研究

氧气在微胶囊膜中的扩散行为将直接决定微囊内细胞的生长代谢行为.以海藻酸钠-壳聚糖聚电解质复合平板膜为研究模型,利用渗透池法,重点考察溶氧在膜中的扩散行为及其影响因素.结果显示:复合膜的扩散系数和孔隙率均低于海藻酸钙,复合膜中溶氧扩散系数为(7～13)×10-10m2·s-1,为水中的23.3％～43.3％,孔隙率为93％～97％;扩散系数随海藻酸钠特性黏度的增大而减小,随壳聚糖分子量的增大而减小.微胶囊膜是氧传质主要的阻力部位,孔隙率、三维结构和材料极性是影响扩散性能的重要因素,改变海藻酸钠特性黏度和壳聚糖分子量可以改变膜孔隙率、结构和材料极性,进而调节膜扩散性能.     

壳聚糖/海藻酸钠可食性保鲜膜的研究进展

近年来由于传统的塑料薄膜生物降解缓慢且污染严重,可食性保鲜膜受到越来越多的关注。可食性保鲜膜具有生物可降解性、环保、实用性好等特点,可应用于各种食品的保鲜,其中壳聚糖、海藻酸钠为常用的成膜材料。本文综述了壳聚糖/海藻酸钠可食性天然抗菌保鲜膜的研究进展,着重介绍材料的来源、分类、改进方向及其在果蔬和肉类保鲜中的应用,并且展望了可食性天然抗菌保鲜膜的研究前景。     

载脂肪酶壳聚糖/海藻酸钙微胶囊的制备

针对固定化脂肪酶的研究背景,以壳聚糖、海藻酸钠为微载体制备材料,采用脉冲电场液滴工艺制备壳聚糖/海藻酸钙微胶囊。以脂肪酶为生物模型,系统考察了制备条件对载脂肪酶壳聚糖/海藻酸钙微胶囊酶活力的影响。结果表明:海藻酸钠质量浓度和酶与海藻酸钠载体配比是影响固定化酶活力的主要因素,载酶量为15mg/mL,海藻酸钠质量浓度为10mg/mL时载酶微胶囊酶活力最高,球形度好。通过改变壳聚糖质量浓度和相对分子质量,可以调控微胶囊膜的厚密程度进而影响固定化酶活力。成膜液pH值依次影响壳聚糖与海藻酸盐分子中官能团的电离状态、成膜反应静电络合程度、酶蛋白包封率,最终影响固定化酶活力。在载酶量为15mg/mL,海藻酸钠质量浓度为10mg/mL,壳聚糖相对分子质量、质量浓度和pH值依次为50kDa、1mg/mL和3.0的条件下,固定化酶活力为187IU/g。     

β-葡萄糖苷酶ACA微胶囊固定化实验研究

对壳聚糖为壁材的共价交联固定、海藻酸钠为壁材的包埋固定及壳聚糖和海藻酸钠共用的新型复合载体(ACA)固定的β-葡萄精苷酶进行了对比研究,得出ACA微胶囊固定化的酶具有较好的催化活性、重复使用和低温贮藏性能.醋酸和戊二醛及CaCl2的浓度、壳聚糖和海藻酸钠用量、引发和交联时间对ACA微胶囊固定酶的形态和性能影响较大,葡萄糖转化率随醋酸与戊二醛和CaCl2浓度的增加、壳聚糖和海藻酸钠用量的增大,交联和引发时间的延长呈先增大后减小的变化趋势,并于不同特定值达到最大.     

有机相中壳聚糖-海藻酸固定化脂酶的特性

研究了壳聚糖 海藻酸固定化脂酶在有机相反应中的稳定性与活性。考察了凝胶时间、壳聚糖浓度及壳聚糖分子质量对固定化脂酶包埋率与活性的影响 ,确定了适宜 pH值与批反应时间。同时讨论了溶剂极性和操作时间对固定化酶稳定性的影响。测定了固定化脂酶水解橄榄油反应的动力学参数。结果表明 ,壳聚糖 海藻酸聚电解质膜可提高固定化酶的包埋率与稳定性     

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     

Antibacterial activity of chitosan–alginate sponges incorporating silver sulfadiazine: Effect of ladder‐loop transition of interpolyelectrolyte complex and ionic crosslinking on the antibiotic release

Hydrogel membranes prepared from polyelectrolyte complex (PEC) have been used for repair of wounds and controlled antibacterial release. A simple method, based on homogenizing interpolyelectrolyte complex, has been developed to prepare a chitosan–alginate sponge with high stability. The spongelike chitosan–alginate hydrogel can be used as a wound dressing for the sustained release of silver sulfadiazine (AgSD) in a controlled way. In this study, we evaluated the effect of electrolyteic properties of chitosan and alginate on the characteristics of the prepared chitosan–alginate PEC. All types of the spongelike chitosan–alginate hydrogels exhibited superabsorbent properties. However, only the chitosan–alginate hydrogel prepared by the interpolyelectrolyte complex of alginate with low pH of chitosan, and that prepared by the interpolyelectrolyte complex of chitosan with high pH of alginate, can keep their stability after swelling in PBS solution. FTIR analysis suggests that the protonated amino groups on chitosan and the ionized carboxylic groups on alginate should be responsible for the formation of a stable ladder‐type of chitosan–alginate PEC. Ionic crosslinking is helpful to increase the stability of the loop‐type of chitosan–alginate PEC. The release of AgSD from chitosan–alginate PEC sponges could be controlled by the variation of ladder‐loop structural transition of chitosan–alginate PEC and the ionic crosslinking of the chitosan–alginate complex. The antibacterial ability of AgSD‐incorporated PEC sponges was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. The result suggests that the PEC sponges containing antimicrobial agents should effectively suppress bacterial proliferation to protect the wound from bacterial invasion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 538–549, 2005     

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     

Anisotropic Chitosan Scaffolds Generated by Electrostatic Flocking Combined with Alginate Hydrogel Support Chondrogenic Differentiation

The replacement of damaged or degenerated articular cartilage tissue remains a challenge, as this non-vascularized tissue has a very limited self-healing capacity. Therefore, tissue engineering (TE) of cartilage is a promising treatment option. Although significant progress has been made in recent years, there is still a lack of scaffolds that ensure the formation of functional cartilage tissue while meeting the mechanical requirements for chondrogenic TE. In this article, we report the application of flock technology, a common process in the modern textile industry, to produce flock scaffolds made of chitosan (a biodegradable and biocompatible biopolymer) for chondrogenic TE. By combining an alginate hydrogel with a chitosan flock scaffold (CFS+ALG), a fiber-reinforced hydrogel with anisotropic properties was developed to support chondrogenic differentiation of embedded human chondrocytes. Pure alginate hydrogels (ALG) and pure chitosan flock scaffolds (CFS) were studied as controls. Morphology of primary human chondrocytes analyzed by cLSM and SEM showed a round, chondrogenic phenotype in CFS+ALG and ALG after 21 days of differentiation, whereas chondrocytes on CFS formed spheroids. The compressive strength of CFS+ALG was higher than the compressive strength of ALG and CFS alone. Chondrocytes embedded in CFS+ALG showed gene expression of chondrogenic markers (COL II, COMP, ACAN), the highest collagen II/I ratio, and production of the typical extracellular matrix such as sGAG and collagen II. The combination of alginate hydrogel with chitosan flock scaffolds resulted in a scaffold with anisotropic structure, good mechanical properties, elasticity, and porosity that supported chondrogenic differentiation of inserted human chondrocytes and expression of chondrogenic markers and typical extracellular matrix.     

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     

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     

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.     

Chitosan/calcium–alginate beads for oral delivery of insulin

A mild chitosan/calcium alginate microencapsulation process, as applied to encapsulation of biological macromolecules such as albumin and insulin, was investigated. The microcapsules were derived by adding dropwise a protein-containing sodium alginate mixture into a chitosan–CaCl₂ system. The beads containing a high concentration of entrapped bovine serum albumin (BSA) as more than 70% of the initial concentration were achieved via varying chitosan coat. It was observed that approximately 70% of the content is being released into Tris-HCl buffer, pH 7.4 within 24 h and no significant release of BSA was observed during treatment with 0.1M HCl pH 1.2 for 4 h. But the acid-treated beads had released almost all the entrapped protein into Tris-HCl pH 7.4 media within 24 h. Instead of BSA, the insulin preload was found to be very low in the chitosan/calcium alginate system; the release characteristics were similar to that of BSA. From scanning electron microscopic studies, it appears that the chitosan modifies the alginate microspheres and subsequently the protein loading. The results indicate the possibility of modifying the formulation in order to obtain the desired controlled release of bioactive peptides (insulin), for a convenient gastrointestinal tract delivery system. © 1996 John Wiley & Sons, Inc.