海藻酸凝胶性质对蛋白质扩散的影响

通过观察冷冻干燥海藻酸凝胶的断面扫描电镜(SEM)照片与卵清蛋白从海藻酸凝胶中的释放试验,分析了海藻酸凝胶性质对蛋白质在凝胶中扩散的影响。凝胶的SEM照片可见,海藻酸钙的冷冻干燥颗粒内为较大的圆孔,海藻酸锌凝胶内为较小的长孔,表明海藻酸锌高分子链在凝胶颗粒中的体积分率相对较大同时刚性较强;卵清蛋白从海藻酸凝胶颗粒中释放的试验结果表明,由于上述海藻酸锌凝胶的特性,导致海藻酸锌对卵清蛋白扩散阻滞作用相对较强;根据试验数据计算得卵清蛋白在海藻酸钙、海藻酸锌凝胶颗粒中的扩散系数分别为1.19×10-7、0.07×10-7cm2/s,利用阻滞模型计算得海藻酸锌高分子链在凝胶颗粒中体积分率约为海藻酸钙高分子链在凝胶颗粒中体积分率的1.7倍。     

一种新型超分子复合水凝胶的制备与性能研究

本文利用合成得到的GLD凝胶因子与海藻酸盐水凝胶制备出一种新型的复合水凝胶GSC,研究了该凝胶的凝胶化转变温度、微观形貌和药物释放行为。当凝胶因子浓度和海藻酸钠浓度增大时,GSC复合水凝胶的三维网络结构会随之变致密,凝胶化转变温度增高,药物释放率降低。盐酸环丙沙星在该水凝胶中的药物释放率还会受到环境pH和温度的影响。     

离子取代凝胶——ACA离子取代动力学模型

用动边界模型描述了海藻酸-壳聚糖-海藻酸(ACA)离子取代凝胶对2价离子的取代动力学过程.模型具有较好的可靠性，ACA离子取代凝胶对2价离子的取代属于颗粒扩散控制.ACA离子取代凝胶对Pb²⁺的反应级数是0.76.     

聚丙烯酰胺改进HD9611菌固定化方法的应用和评价

利用阳离子聚丙烯酰胺（PAM）的物理和化学作用,对海藻酸钡凝胶固定化HD9611菌方法进行了改进;并开展了PAM凝聚法直接固定化该细胞生产丙烯酰胺（AM）的研究。上述方法与海藻酸钡凝胶包埋法比较结果表明,在生产工艺和效率、产品质量及成本等方面效果都比较显著。     

PAM强化海藻酸钡凝胶制备固定化细胞研究

通过选择与所固定细胞表面所带相反电荷的聚丙烯酰胺(简称PAM)制成PAM-海藻酸钡复合凝胶,并与普通海藻酸钡凝胶进行比较。结果证明,先在菌悬液中加入30～50mg／L的阳离子PAM,使菌株絮结成微团,再加入1．2％～1．6％海藻酸钠和0．1％～0．2％的阳离子PAM,在1．5mol／L BaCl2溶液中固化成型的固定化细胞,能提高腈水合酶的利用率30.3％。同时,该凝胶的机械强度、使用寿命、酶活稳定性等性质也优于普通海藻酸钡凝胶。     

海藻酸的疏水改性及其性能表征

海藻酸与辛胺反应合成疏水的海藻酸辛酰胺,对其进行1H-NMR、元素分析等表征。分析海藻酸接枝后溶液表面张力的变化;研究不同接枝率、p H对海藻酸辛酰胺临界缔合浓度的影响;并以疏水改性的海藻酸作囊材,制备高效氯氟氰菊酯微胶囊。结果表明:疏水改性后海藻酸溶液表面张力减小;随着接枝率、体系p H增加,海藻酸辛酰胺临界缔合浓度下降;通过乳化凝胶技术,制得平均粒径12.86μm的疏水海藻酸衍生物微胶囊。     

海藻酸纤维在医用敷料中的应用

近年来,由海藻酸纤维制成的非织造布在医用敷料上得到了广泛的应用,比起传统的棉纱布,海藻酸纱布吸湿性高,止血性能好,并能在潮湿的伤口表面形成一层水凝胶,这层水凝胶体既能给伤口提供一个良好的愈合环境,又能在伤口复愈后无疼痛地去除,从而使海藻酸纱布拥有其独特的伤口保护性能。本文介绍了海藻酸纤维的制造工艺及物化性能,并对海藻酸纱布的临床应用作了一些描述。     

组织工程用海藻酸盐水凝胶的研究进展

海藻酸钠已经被广泛应用于生物医学领域。本文从组织工程角度出发,综述了海藻酸盐水凝胶的形成机理、制备方法以及应用研究进展。     

海藻酸镁凝胶的制备及其性能研究

在0.05～5 mol/L镁离子浓度范围内制备了一系列具有不同性能的海藻酸镁凝胶，考察了镁离子浓度、镁离子用量、镁盐种类和海藻酸钠M/G比值等因素对海藻酸镁凝胶成胶过程的影响，并测试了不同制备条件下凝胶的力学性能和溶胀性能。结果表明，高离子浓度可将海藻酸镁凝胶的拉伸强度提高到400 kPa以上；采用氯化镁、溴化镁、乙酸镁制备的凝胶力学性能较好。同时海藻酸镁具有成胶慢的特点，不同的制备条件可使凝胶形成时间在1 min～10 h内发生变化，显示了其在可注射水凝胶方面具有良好的应用前景。     

超低粘度海藻酸

公津化学工业公司成功地开发了超低粘度海藻酸。海藻酸是褐色海藻的主要成分,它广泛用作为食品加工、纤维加工和药物制造工业中的稀释剂和细胞组织稳定剂。但用传统方法制取的海藻酸,由于在胶     

Tunable transport of glucose through ionically‐crosslinked alginate gels: Effect of alginate and calcium concentration

Alginate beads have numerous biomedical applications, ranging from cell encapsulation to drug release. The present study focuses on the controlled release of glucose from calcium‐alginate beads. The effects of alginate concentrations (1–6 wt %) and calcium chloride concentrations (0.1–1.0M) on glucose release from beads were examined. It was found that the time required for complete glucose release from beads could be tuned from 15 min to over 2 h, simply by varying alginate and calcium chloride concentrations in beads. For calcium‐alginate beads with sodium alginate concentrations of 1–4 wt %, higher sodium alginate concentrations lead to more prolonged release of glucose and thus a smaller value of a rate constant k, a parameter shown to be proportional to the diffusion coefficient of glucose in the alginate gel. For beads with sodium alginate concentrations of 4–6 wt %, there was no statistically significant difference in k values, indicating a lower limit for glucose release from calcium‐alginate beads. Similarly, higher calcium chloride concentrations appear to extend glucose release, however, no conclusive trend can be drawn from the data. In a 50 : 50 mixture of calcium‐alginate beads of two different alginate concentrations (1 and 4 wt %), glucose release showed a two‐step profile over the time range of 20–50 min, indicating that the pattern and time of glucose release from beads can be tuned by making combinations of beads with varying alginate and/or calcium chloride concentrations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Controlled release study of carbaryl insecticide from calcium alginate and nickel alginate hydrogel beads

In this study, controlled release formulations for reducing environmental impact of pesticides have been produced by encapsulating as a model pesticide carbaryl (Carb) in the alginate beads. The various hydrogel bead formulations were prepared by the ionotropic crosslinking of sodium alginate (NaAlg) with calcium and nickel ions. The surface morphology of prepared beads was characterized with scanning electron microscopy (SEM). SEM confirmed the spherical nature and surface morphology of the particles. Bead characteristics, such as carbaryl entrapment efficiency, particle size, equilibrium swelling degree, and carbaryl release kinetics, were determined. The effects of the bead preparation conditions such as crosslinker concentration and type, carbaryl/sodium alginate (Carb/NaAlg) ratio and percentage of NaAlg on the carbaryl release from the calcium alginate (Ca‐Alg) and nickel alginate (Ni‐Alg) beads were investigated in distilled water at 25°C. It was observed that carbaryl release from the Ca‐Alg beads was slower than that of Ni‐Alg beads. The release results indicated that carbaryl release from both of the Ca‐Alg and Ni‐Alg beads decreases with the increasing crosslinker concentration, Carb/NaAlg ratio and percentage of NaAlg. The highest carbaryl release was found to be 100% for the Ni‐Alg beads at 3 days whereas the lowest carbaryl release was found to be 67% for the Ca‐Alg beads at 21 days. The swelling measurements of the beads were also in consistent with the carbaryl release results. The carbaryl release from most of the bead formulations followed Case II transport. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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     

Preparation of phycocyanin microcapsules and its properties

Phycocyanin was microencapsulated by an extrusion method using alginate and chitosan as coating materials. This work was aimed to optimize the encapsulation process, characterize the physicochemical properties of microcapsules, and evaluate the storage stability and in vitro release performance. The optimum process conditions for preparing microcapsule gained from the single factor experiments were as follows: alginate content 2.5%, ratio of phycocyanin to alginate 1.5:1, content of calcium chloride 2.5%, and chitosan content 2.0%. Phycocyanin/alginate/chitosan microcapsules (PACM) were found to have compact spherical shape with mean diameters of 1.03 mm, whereas phycocyanin/alginate microspheres (PAM) were internal porous spherical appearances with mean diameters of 1.81 mm. Storage stability study showed that encapsulation by alginate and chitosan conferred greater ability to phycocyanin against temperature during storage. In vitro release study revealed that both PAM and PACM could be resistant against acidic environment, and would rapidly release phycocyanin under mild alkali condition. The sustained-release profile of phycocyanin from PACM was superior to that from PAM.     

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     

Swelling and drug release behavior of calcium alginate/poly (sodium acrylate) hydrogel beads

In the present work calcium alginate/poly (sodium acrylate) composite beads have been prepared by in situ formation of cross-linked poly (sodium acrylate) network, within the calcium alginate (CA) beads. The CA/poly (SA) beads have been found to be stable for more than 48 h, in the physiological fluid (PF) of pH 7.4, while the plain alginate beads disintegrated within a couple of hours. The water uptake of beads was investigated under various composition parameters such as the amount of alginate, concentration of ionic cross-linker Ca⁺⁺ ions, monomer sodium acrylate (SA) contents, and degree of cross-linking. The beads also exhibited fair stability in the media of varying pH. Finally the release of model drug methylene blue (MB) was investigated. It was found that plain CA and CA/poly (SA) composite beads exhibited different release mechanisms.     

海藻酸锌纤维

海藻酸锌纤维是一种具有优良生物活性的功能性纤维材料,可以通过湿法纺丝直接制备,也可以通过对海藻酸钙纤维进行离子交换间接制备。在间接法制备海藻酸锌纤维的过程中,可以通过控制海藻酸钙纤维与锌盐的质量比例得到含不同浓度锌离子的纤维。由于纤维中含有对伤口的愈合有促进作用的锌离子,海藻酸锌纤维通过持续释放锌离子在医用敷料的生产中有特殊的应用价值。试验结果表明:海藻酸锌纤维在释放锌离子的过程中可以起到抑制细菌增长的作用,在医疗卫生领域具有特殊的应用价值。     

Preparation of polyethersulfone–alginate microcapsules for controlled release

In this study, polyethersulfone (PES)–alginate microcapsules were prepared for drug‐controlled release, and vitamin B₁₂ (VB₁₂), rifampicin (RFP), and bovine serum albumin (BSA) were used as model drugs. Different microcapsules were prepared by the variation of the crosslinking degree of alginate and the variation of the chemical components of the microcapsule membrane, including the PES and polyethylene glycol (PEG) contents. Systematic experiments were carried out to study their influences on the release profile of the model drugs. The results showed that with the increase of the crosslinking degree of the alginate, the drug release rate increased; whereas with the increase of the PES concentration used to prepare the microcapsule membrane, the drug release rate decreased. The contents of the PEG in the microcapsule membrane also affected the drug release. This study enriched the methodology of the fabrication of the microcapsules, and the microcapsules may have a potential use for controlled release. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Alginate and Sulfanilamide Based DDS with Antibacterial Activity

The aim was to obtain alginate based, biological active delivery systems, with prolonged release of sulfanilamide. The influences of alginate gel concentration as well as the influence of sulfanilamide content were studied. The presence of sulfanilamide assures antimicrobial activity while alginate and magnetite are responsible with the slow release kinetic. The presence of magnetite is also important because allows magnetic field guidance of the alginate/Fe₃O₄/sulfanilamide beads. The obtained DDS were characterized by FTIR, SEM, release profile in saline solution (0.9% NaCl), and antimicrobial activity against Escherichia coli.