APS－TU引发丙烯酸酯类单体与海藻酸钠的接枝共聚

以过硫酸铵（ＡＰＳ）与硫脲（ＴＵ）组成引发体系，研究甲基内烯酸甲酯（ＭＭＡ）、甲基丙烯酸缩水甘油酯（ＧＭＡ）、甲基丙烯酸乙酯（ＥＭＡ）、丙烯酸甲酯（ＭＡ）分别与海藻酸钠（ＳＡ）的接枝共聚反应，ＩＲ及Ｘ－射线粉末衍射表征了产物的结构。当［ＡＰＳ］＝［ＴＵ］＝（６－８）×１０￣（－３）ｍｏｌ／Ｌ、［Ｍ］＝０．６ｍｏｌ／Ｌ、ＳＡ＝２．０ｇ／１００ｍｏｌ、６０℃、反应４ｈ时，所得接枝共聚物的接枝率（Ｇ）及接枝效率（Ｅ）值最佳。单体接枝活性顺序为：ＭＭＡ＞ＧＭＡ＞ＭＡ＞ＥＭＡ。     

Microencapsulation of Bifidobacterium animalis subsp. lactis in Modified Alginate-chitosan Beads and Evaluation of Survival in Simulated Gastrointestinal Conditions

Bifidobacterium animalis subsp. lactis was entrapped in alginate, alginate-chitosan, alginate-chitosan-Sureteric and alginate-chitosan-Acryl-Eze. Survival and in vitro release of bifidobacteria from the microparticles were investigated under conditions simulating gastrointestinal fluids covering the pH range from 1.5 to 7.5, with and without pepsin (3gL^-1), pancreatin (1gL^-1), and bile (10gL^-1). All types of microcapsules protected B. animalis, but the use of chitosan and enteric polymers in the formulation of the beads, especially Acryl-Eze, enhanced the beneficial effects of the microencapsulation technique. Besides promoting the controlled release of bifidobacteria in simulated gastrointestinal juices, the microencapsulation with enteric polymers improved the survival rate of these microorganisms.     

Design considerations for an immobilized cell bioreactor operating in a batch recirculation mode

Immobilizing microbial cells and enzymes used in biological and biochemical processes is advantageous and has been a subject of intensive study in recent years. Successful implementation of this technology requires complete understanding of physical, chemical and biological parameters which influence the performance of such a system. This paper focuses on a few basic design considerations which are essential to the design and operation of immobilized cell bioreactors. A process using microorganisms entrapped in calcium alginate gel as a biocatalyst is considered. This system is used to biodegrade the organic compound, phenol. A batch reactor operated in a recirculation mode is used, and parameters like concentration of dissolved oxygen, concentration of the organic compound, bead size, biomass loading and the flow rate are studied. The bioreactor can be operated within many operating windows where one of the above parameters may be rate limiting. With the help of conceptual and experimental data, the influence of the above parameters on the reaction rates is discussed.     

海藻纤维与不同金属离子配位反应动力学的比较研究

将海藻纤维与Fe3+、Cu2+和Ce3+3种金属离子分别进行配位反应,在考察了金属离子初始浓度和反应温度对配位能力影响的基础上,研究了不同金属离子的配位反应特性,并计算和比较了相关的动力学参数。结果表明,海藻纤维能与3种金属离子发生配位反应生成海藻纤维金属配合物,金属离子初始浓度提高可使其配合量呈线性增加。此配位反应不仅符合Langmuir和Freundlich等温吸附模型,而且属于一级动力学反应,升高温度能使反应速率常数增大。3种金属离子的配合量和反应速率常数依下列顺序排列:Fe3+Cu2+Ce3+,而其反应活化能则表现出相反趋势,说明Fe3+和Cu2+比Ce3+更易于与海藻纤维发生配位反应。     

Effects of Polymeric Stabilizers on the Synthesis of Gold Nanoparticles

Gold nanoparticles （AuNPs） stabilized with sodium alginate （SA）, glycol chitosan （GC）, polyvinyl alcohol （PVA）, and polyethyleneimine （PEI） were synthesized in aqueous solutions at room temperature. Different sizes and size distributions of AuNPs were obtained according to the polymeric stabilizers. The mean particle diameters of AuNPs synthesized with GC and PVA as stabilizers were about 5.1 and 5.3 nm, respectively, while those of AuNPs stabilized with SA and PEI were 8.4 and 10.8 nm, respectively. When SA was used, relatively large particles aggregated to form large clusters. In the case of GC, a number of small particles built up large clusters. When PVA was used, the size and the number of nanoperticles were estimated small with a low weight content of Au. For this reason, the PVA-stabilized AuNPs formed clusters with a small hydrodynamic size. The AuNPs synthesized in the aqueous solution of PEI without a reducing agent, sodium borohydride, were uniform in size and formed the smallest nanoclusters （67.4 nm）. In this case, the highest Au content was obtained. Sufficiently grown nanoparticles with a high Au content and a limited hydrodynamic size are considered to be suitable for a variety of applications.     

Alginate drug delivery systems: application in context of pharmaceutical and biomedical research

Alginates are natural polymers widely used in the food industry because of their biocompatible, biodegradable character, nontoxicity and easy availability. The bioadhesive character of alginates makes them useful in the pharmaceutical industry as well. The application areas of sodium alginate-based drug delivery systems are many and these systems can be formulated as gels, matrices, membranes, nanospheres, microspheres, etc. Worldwide researchers are exploring possible applications of alginates as coating material, preparation of controlled-release drug delivery systems such as microspheres, beads, pellets, gels, fibers, membranes, etc. In the present review, such applications of alginates are discussed.     

海藻酸钙水凝胶过滤膜的制备及其对硫酸钙的截留

以尿素为致孔剂制备了海藻酸钙(CA)水凝胶过滤膜,测试了其通量、截留率和力学性能;通过扫描电子显微镜(SEM)观测其过滤硫酸钙前后的表面形貌。结果表明,增加尿素含量,均导致膜应力和应变的下降;而膜的纯水通量则迅速增大,尿素含量为3.0%(质量分数)时达到28.7 L/(m2·h),为最大;0.2 MPa下,过滤1.7 g/L硫酸钙时对Ca2+和SO2-4的截留率分别为83%和92%,稳定通量达到21.7 L/(m2·h)。     

氧化海藻酸钠交联壳聚糖载药复合体系的制备及其药物缓释初步研究

为获得一种新型的药物释放复合体系,本实验首先通过乳化交联法制备壳聚糖(CS)包载四环素(TC)微球,然后利用氧化海藻酸钠交联聚磷酸钙/壳聚糖(CPP/CS)复合材料,用冷冻干燥法制备了载药微球复合体系.并用傅立叶红外光谱仪(IR)、扫描电镜(SEM)及药物的体外释放等方法对该载药微球复合体系进行分析和表征.结果显示,经...