壳聚糖/聚乙烯醇微球吸附脲酶的特性及其动力学

目的制备壳聚糖/聚乙烯醇(PVA)微球脲酶,探讨其最适温度、最适pH、热稳定性及其动力学。方法用微乳法制备壳聚糖/PVA微球,采用电子扫描电镜表征其形态;用吸附法获得壳聚糖/PVA微球脲酶;运用Berthlot测定其活力。结果壳聚糖/PVA微球脲酶酶活性保持率是原酶的91.93%,最适温度为47℃,最适pH6.5,热稳定性明显高于溶液脲酶;壳聚糖/PVA微球脲酶的动力学参数KM=11.8 mmo.lL-1,Vm ax=37.1μmo.lm in-.1mg-1。结论壳聚糖/PVA微球脲酶可制备成用于尿毒症患者的口服制剂。     

壳聚糖微球制备方法研究

综述近年来国内外壳聚糖微球制备方法的研究进展,其中主要介绍交联法、凝聚法、乳化-溶剂蒸发法、壳聚糖溶液包衣法、壳聚糖微球乙酰化法、喷雾干燥法等。     

壳聚糖微球的研究进展

壳聚糖是天然聚合物甲壳素脱乙酰基产物,具有独特的物理化学及生物学特征,是制备缓释、控释制剂较理想的高分子材料,已引起人们的广泛兴趣。本文综述壳聚糖微球的制备方法,影响壳聚糖微球的制备及药物释放的因素,以及壳聚糖微球的作用特点等。     

聚乙烯醇微球的制备与研究

目的:制备聚乙烯醇微球,用于静脉注射靶向给药研究。方法:通过将溶有戊二醛的乙醚加入到以聚乙烯醇水溶液为水相、正庚烷为油相的乳液中作为交联剂,将微量浓盐酸滴加到乳液中作为催化剂,乳化聚合制备出聚乙烯醇微球,并考察了聚乙烯醇溶液浓度、搅拌速度及油水相比例等对微球粒径及形貌的影响。结果:在聚乙烯醇浓度为5.0%,搅拌速度为14000r·min~(-1)条件下,制备的微球平均粒径为1.9μm。且聚乙烯醇浓度越高,微球平均粒径越大,单分散性越差;搅拌速度越高,微球平均粒径越小,单分散性越好。结论:通过调整聚乙烯醇浓度和搅拌速度,可以得到1～15μm范围内不同平均粒径的微球。     

环丙沙星壳聚糖微球的制备

以戊二醛作为交联剂,采用反相乳化法制备支气管镜介入治疗用环丙沙星壳聚糖微球.采用单因素法和正交试验优化了处方中影响制品外观、平均粒径、载药量和包封率的因素.按优化处方制备的微球外观圆整,平均粒径(142.31±7.85) μm,载药量(14.20±0.61)％,包封率(56.43±1.31)％.体外释放行为符合Higuchi方程,2h和48 h时累积释放率分别为44.3％和92.1％,提示制品具有缓释效果,有利于减少给药频次.     

壳聚糖微球的制备及其在药物载体中的应用进展

壳聚糖因其具有独特的物理、化学及生物学特性,目前已经成为制备缓释和控释制剂的十分理想的天然高分子材料,且壳聚糖微球作为药物缓释形式也受到越来越多的关注.现综述壳聚糖徼球的缓释机制、制备方法及其在药物载体中的应用进展.     

紫杉醇壳聚糖肺靶向微球的制备

目的研制具有肺靶向性的紫杉醇壳聚糖微球,并对处方工艺进行优化。方法以壳聚糖为载体,采用乳化一化学交联法制备紫杉醇壳聚糖微球。单因素试验考察了油／水体积比、紫杉醇浓度、乳化时间、乳化剂量等因素,采用正交设计优化微球制备工艺,以HPLC法测定微球载药量、包封率。结果制得的微球显微观察形态圆整、表面光滑,无黏连;平均粒径为（8．23±0．25）μm,粒径在7～12μm平均占微球总数的84．2％,载药量为16．20％±1．15％,包封率为81．29％±1．62％。结论筛选的最佳处方工艺制备的微球粒径大小适宜,可满足肺靶向微球的要求并免除过敏试剂的加入。     

磁性壳聚糖微球的制备和条件优化

目的:探讨磁性壳聚糖微球的制备和条件优化.方法:制备磁性流体,加入壳聚糖、碱性硅溶胶、尿素后调节pH值,再加入甲醛交联固化即得磁性壳聚糖微球.观察微球对酸碱的耐受性,分析壳聚糖的包裹情况.结果:当磁流体溶液、壳聚糖溶液、碱性硅溶胶溶液的加入量均为25mL,尿素的加入量为2.25g,甲醛加入量为3mL时制的磁性壳聚糖微球粘连最少,并且球形较好,耐酸碱性也较好,也就是说,壳聚糖:硅胶:Fe3O4的质量比为5∶5∶1,尿素的加入量为3g/100mL,甲醛的加入量为4mL/100mL是制备磁性壳聚糖微球的较好条件.结论:此条件下制得的磁性壳聚糖微球比较稳定,大小比较均匀,并且这种条件下制成的微球耐酸碱.     

新型交联壳聚糖微球的吸附性能研究

目的 通过电位分析方法 ,研究不同含量氨基、外加介质钠盐和不同类型酸对交联壳聚糖微球吸附低浓度游离酸的影响,优化生产工艺.方法 利用固-液相互作用方程,求取吸附剂-吸附质相互作用能.结果 表观吸附速率常数k随活性中心数目G、吸附剂-吸附质相互作用能U的增加而增大,随外加介质钠盐而减小.结论 交联壳聚糖微球吸附游离酸的过程,k与G、U存在线性相关性.     

壳聚糖—聚乙烯醇复合膜的研制

在壳聚糖膜的基础上,用聚乙烯醇成功改性了壳聚糖膜,研制出复合膜,使膜的透气率、合水率均得到很好的改善。     

甲硝唑羧甲基壳聚糖缓释微球的制备及体外释放

目的:探讨乳化交联法制备甲硝唑羧甲基壳聚糖微球的最佳工艺,并了解微球体外释药规律.方法:按正交设计,考察不同羧甲基壳聚糖浓度、投药比、交联度、乳化转速等条件对质量指标的影响,选出最佳方案,并进一步检测微球的体外释放特性.结果:各因素对所制微球综合评分指标的影响大小依次为:乳化转速>投药比>交联度>羧甲基壳聚糖浓度,用优化的工艺制得微球50～200μm粒径分布百分数为48.86%,载药量为48.19%,包封率为37.46%,在pHI.2、6.8和7.6,3种缓冲液中的释放时间为6～8h.结论:本法所制微球工艺稳定.在体外具有缓释作用.     

新型胺基壳聚糖微球的制备及对黄酮类物质的吸附性能

目的制备1种新型胺基壳聚糖微球,并以山楂叶中的黄酮类化合物为吸附模型,研究其吸附性能。方法采用反相悬浮交联法制备壳聚糖微球,甲醛为预交联剂,经羟丙基化、胺基化,并通过红外光谱,扫描电镜测定其结构。结果改性壳聚糖微球对游离黄酮的吸附量大于壳聚糖的吸附量,9 h后基本达到吸附平衡,通过此法得到的最优的多孔壳聚糖吸附剂对黄酮类化合物的吸附量在600 mg/g以上。结论该法制得的壳聚糖微球是1种良好的多孔吸附剂,有较好的工业化前景。     

Preparation of doxorubicin-containing chitosan microspheres for transcatheter arterial chemoembolization of hepatocellular carcinoma

A new form of doxorubicin hydrochloride (DRH)-containing chitosan microspheres (CMs) was prepared by employing an expanding-loading-shrinking (E-L-S) process. One hundred mg of pre-formed CMs were soaked in absolute ethanol and then placed in reduced pressure (the expanding process). Ten mg of DRH (2?mg?ml^?1) were added into the expanded CMs (the loading process). Next the microspheres were freeze-dried (the shrinking process). As a result of this E-L-S process, 10% (w/w) DRH-containing CMs (DRH-CM) were made. During 7 days, 22.6% of the DRH was observed to be released on the in vitro drug release study. In addition, these new DRH-CMs could be used for transcatheter arterial chemoembolization (TACE) procedure in VX2 hepatic tumour models of rabbit and the anti-tumour effects of DRH-CMs were investigated. On the post-CT scan 7 days after the TACE, total infarctions of the VX2 tumour were observed in 5 rabbits among the 6 total rabbits.     

包埋PLGA微球壳聚糖支架的构建及其对蛋白释放的调节

目的制备能缓慢释放蛋白类药物的细胞生长支架。方法采用冷冻干燥制备壳聚糖支架，测定支架的孔隙率和吸水率。以牛血清白蛋白(BSA)为模型药物，制备乳酸-羟乙醇酸共聚物(PLGA)微球，并包埋于壳聚糖支架中，用扫描电镜观察微球和支架的形态，考察药物在各种支架上的体外释放。结果壳聚糖支架为多孔结构，当预冻温度为-70 ℃时，支架的孔隙率和吸水率分别为78.6%±1.5%和85.1%±6.2%。PLGA微球能够较均匀地覆在壳聚糖支架上。单用壳聚糖支架，BSA在24 h累积释放达90%以上，制成PLGA微球后，再包埋于壳聚糖支架中，则药物释放明显缓慢，168 h的累积释放量为33.5%。通过改变壳聚糖的用量和PLGA材料的型号，可以调控药物在复合支架上的释放。结论包埋PLGA微球的壳聚糖支架有望用于组织工程的支架材料和生长因子的缓慢释放。     

Preparation of chitosan microspheres using membrane emulsification and its size modelling

The chitosan microspheres were prepared by a membrane emulsification method with variations of the N₂ gas pressure and the chitosan concentration. The pressure of N₂ gas was varied within the range from 0.2?×?10⁵ to 0.8?×?10⁵?Pa at chitosan concentration 1.5?wt%. In addition, the concentration of chitosan was varied between 0.5?～?2.0?wt% at 0.4?×?10⁵?Pa of N₂ gas pressure. Using this method, it is possible to prepare stable emulsions with a very narrow droplet size distribution in comparison with conventional methods. The average size of the microspheres was dependent on the N₂ gas pressure and the concentration, that is it was increased with the pressure and the concentration. The modelling of the size for the microspheres according to the concentration was carried out using Macleod's relation and Parkins & Brown equation. The former shows the relationship between density and surface tension and the latter demonstrates the correlation between the volume of the microspheres and the interfacial tension. The modelling results were in good agreement with the experimental data to predict the microspheres size with the variation of concentration.     

微球的制备和表征

目的制备葡激酶突变体(K35R，DGR)的聚乳酸-羟基乙酸(PLGA)微球，使其在包封和释放过程中都能保持活性。方法使用复乳溶剂挥发法制备DGR的PLGA微球，研究了搅拌速度、PLGA浓度、内水相和外水相中的添加剂对蛋白包封率以及微球性质的影响，并进行了DGR微球的体外和体内释放试验。结果2%聚乙烯醇可以有效抑制超声乳化时DGR在水/二氯甲烷界面上的变性，将DGR的活性回收率从16%提高到几乎100%。在外水相中加入NaCl可以显著提高蛋白包封率，同时对微球的粒径分布和表面形态也产生了重要影响。DGR微球的体外释放呈现两个时相，15 d释放大约DGR总活性的50%。DGR微球在体内持续释放5 d。结论制备的PLGA微球，DGR包封率高，稳定性较好，是DGR的良好载药系统。     

Fabrication of porous polyethyleneimine-functionalized chitosan/Span 80 microspheres for adsorption of diclofenac sodium from aqueous solutions

Porous surface-modified microspheres can have widespread applications in the removal of wastewater pollutants. In this study, using a nonionic surfactant (Span80) as the pore-forming agent and Zr⁴⁺ as the cross-linking agent, polyethyleneimine (PEI)-modified porous CYCTS/Span80 microspheres ((CYCTS/Span80)-@-PEI) were successfully prepared for the adsorptive removal of diclofenac sodium (DS) from wastewater. The adsorbent was characterized using Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectrometry, scanning electron microscopy, and X-ray diffractometry. The activity of the porous (CYCTS/Span80)-@-PEI microspheres as adsorbents of DS was investigated by varying the experimental parameters (i.e., adsorbent dosage, adsorbent ratio, pH, contact time, temperature, and pollutant concentration). A possible adsorption mechanism was also discussed. The experimental results showed that the adsorption process followed a pseudo-second order kinetic model and the Langmuir adsorption isotherm model, in addition to the Freundlich isotherm model, indicating that the porous structure allowed multi-layer adsorption. Adsorption equilibrium was reached after 240 min at pH 5 and 303 K, yielding a maximum adsorption capacity of 572.67 mg/g. After five adsorption cycles, the removal rate of DS remained >80%, and the recovery rate was high. Therefore, we concluded that the porous (CYCTS/Span80)-@-PEI microspheres are efficient and inexpensive candidates for the removal of DS from wastewater.     

羧甲基壳聚糖/聚乙烯醇水凝胶处方及制备工艺优化

目的：优选羧甲基壳聚糖（CMCS）／聚乙烯醇（PVA）水凝胶的处方及制备工艺；初步考察载药水凝胶的体外释药规律。方法：合成不同取代度的CMCS；以羧甲基壳聚糖的取代度，2％戊二醛的用量及温度为考察因素，各取三水平，以水凝胶在pH1．2溶液中的膨胀率为考察指标进行L9（3^4）正交实验；并以甲硝唑为模型药物，对水凝胶的体外释药做初步考察。结果：取代度为0．38的CMCS，在0．2mL的2％戊二醛做交联剂于室温下交联，有最大膨胀率（24．54±1．04）（n=3）；以最佳条件制备的甲硝唑水凝胶于0．1mol·L^-1盐酸溶液中在8h内累积释药率达（89．95±1．05）％（n=3）。结论：CMCS/PVA水凝胶最佳处方在pH1．2时具有理想的膨胀率，可做为胃部释药载体进一步研究。