Mechanical strength of single microcapsules determined by a novel micromanipulation technique

A micromanipulation technique has been developed to measure the bursting force of single dry microcapsules coated onto a surface, such as those normally used in carbonless copying paper. For measuring the bursting force of a given microcapsule, a single fine probe with a flat end about 10mum in diameter was used to squeeze the microcapsule against a flat surface until it burst. The force being imposed on the microcapsule was measured by a transducer connected to the probe. The bursting force and diameter of single dry microcapsules in two samples, different in size and wall thickness, were measured by this technique. The bursting force of the microcapsules in one sample ranged from 50 to 220muN and the diameter from 1.3 to 7.0mum, whilst the bursting force in the other was from 20 to 175muN and the diameter from 0.7 to 3.7mum. This technique makes it possible to compare the mechanical strength of microcapsules made of different formulations, and to infer information about microcapsule mechanical properties.     

The relation between narrow-dispersed microcapsules and surfactants

Electric ink display is one of the prospect technologies in paper-like display. In this paper, electric ink microcapsules are prepared by means of an in situ polymerization and complex coacervation. In order to obtain the microcapsules in a uniform size distribution, this study focused on the inter-facial tension between tetrachloroethylene and water solution, the dispersion of the core droplets and the microencapsulation with different kind of surfactants. By measuring the inter-facial tensions between water and tetrachloroethylene, it is found that urea-formaldehyde (UF) pre-polymer presents certain surface activity due to the inter-facial tension descending from 43?mN?m^?1 to 35?mN?m^?1. Because the surface activity of pre-polymer is not valid, the water-soluble emulsifiers can occupy on the surface of the droplets and prevent the UF resin depositing there. The analysis of the size distribution shows that the UF microcapsules are multi-dispersed. Furthermore, the influence of anionic surfactant of SDS on the size distribution of the core droplets is also investigated. The average diameters of the core droplets prepared with 0.005?wt% and 0.012?wt% SDS are?～50?µm and 28?µm, respectively. That reveals the existence of SDS not only decreases the droplet diameters, but also makes the size distribution centralized. Because the surface of the core droplets is charged due to the absorption of SDS anionic, the Gelatin and Gum Arabic (GA) coacervating layer is easy to form there. The size of the GA microcapsules prepared with 0.003?wt% SDS is?～65?µm. Finally; the responsive behaviour of the microcapsules to electric field is also investigated.     

Gastroresistant microcapsules: new approaches for site-specific delivery of ketoprofen

Ketoprofen is a potent non-steroidal anti-inflammatory drug (NSAID) that has been widely used in the treatment of rheumatoid arthritis and other related conditions. However, it carries the risk of undesirable systemic side effects and gastrointestinal irritation at the usual dose of oral administration. The aim of this study was to prepare and evaluate gastroresistant microcapsules containing ketoprofen. Microcapsules were obtained by a spray-drying process starting from an O/A emulsion in the presence of different pH-dependent materials (Eudragit^® L100, Eudragit^® S100, and stearic acid) dissolved in the external phase. The influence of formulation factors (oily phase employed for drug solubilization, type of coating) on the morphology, particle size distribution, drug loading capacity, in-vitro release, and ex-vivo permeation characteristics were investigated. Drug loading capacity was very high for all the microcapsules prepared. Formulation factors did not significatively influence the mean particle size, but modified microcapsule in-vitro and ex-vivo behavior.     

正交试验优选白藜芦醇微囊处方

目的：优选白藜芦醇微囊的处方。方法：采用滴制法制备白藜芦醇微囊,以海藻酸钠黏度、海藻酸钠与白藜芦醇质量比、海藻酸钠质量分数、氯化钙质量分数为考察因素,以白藜芦醇载药量和包封率的综合评分为评价指标,采用正交试验优选白藜芦醇微囊处方。结果：最优处方为海藻酸钠黏度为380cps、海藻酸钠与白藜芦醇的质量比为0．5：1、海藻酸钠质量分数为2．0％、氯化钙质量分数为3．0％。结论：所选白藜芦醇微囊处方合理,制得的白藜芦醇微囊裁药量和包封率较高。     

微囊化成骨细胞诱导骨髓间充质干细胞体外成骨分化的量效研究

目的探讨微囊化成骨细胞体系细胞添加量对诱导骨髓间充质干细胞体外成骨分化的影响。方法制备含有成骨细胞的海藻酸钠-聚赖氨酸-海藻酸钠微囊,与间充质干细胞的共培养,在1,7,14 d通过细胞增殖量、碱性磷酸酶活性、实时定量PCR等检测,统计结果并分析。结果各时段细胞增量无统计学意义;碱性磷酸酶活性随细胞浓度增加表现出递增趋势,且骨钙蛋白mRNA的表达结果基本一致。结论微囊化成骨细胞在低浓度下已能促进骨髓间充质干细胞成骨分化,浓度升高时促分化能力越强,但达到一定浓度后继续提高时,对成骨分化的作用则不再增强。     

Effect of viscosity and concentration of wall former, emulsifier and pore-inducer on the properties of amoxicillin microcapsules prepared by emulsion solvent evaporation

This study reports the laboratory optimization for the preparation of sustained release amoxicillin (AMX) ethylcellulose microcapsules by an emulsion solvent evaporation process by adjusting the viscosity and concentration of ethylcellulose, ratio of amoxicillin to ethylcellulose, and concentration of emulsifier and pore inducer. When ethylcellulose with a viscosity of 45 mPa.s was used, almost no material stuck to the inside wall of the beaker and uniform microcapsules were prepared. The average diameter of microcapsules increased and yield and release rate decreased as the concentration of ethylcellulose increased from 1% to 8%. The release of amoxicillin from microcapsules was influenced by the ratio of the weight of drug to that of ethylcellulose and ratios of 2:1 and 4:1 were most suited for optimum amoxicillin release. The average diameter of microcapsules decreased and the release rate increased as the concentration of the emulsifier increased from 1.5% to 6.0%, however, the size distribution became significantly wider with the increase in the concentration of sorbitan monooleate. Addition of small amounts of a water-soluble agent sucrose improved the release of active ingredient from the microcapsule matrix without influencing the morphology and particulate properties of the microcapsules.     

RP-HPLC测定番茄红素微胶囊的含量

目的建立反相高效液相色谱法测定番茄红素微胶囊中番茄红素含量的方法。方法采用反相高效液相色谱法,色谱柱为美国Alltech Alltima C1（84.6mm×250mm,5μm）,流动相为甲醇-四氢呋喃-水（66∶30∶4,V/V/V）,流速为1.5mL·min^-1,检测波长为472nm。结果线性范围为 3.6～18μg·mL^-1,相关系数r=0.9998,平均回收率为99.81%～101.06%,RSD为1.12%～1.83%,日内和日间精密度的RSD分别在1.73%～2.54%、2.85%～3.34%之间。结论本文采用反相高效液相色谱法初步建立了番茄红素微胶囊中番茄红素的定量方法, 该方法准确, 快速, 重现性好。     

海藻酸-壳聚糖-聚乙烯乙二醇微囊生物相容性的研究

目的比较海藻酸-壳聚糖-聚乙烯乙二醇微囊(ACP微囊)和海藻酸-聚赖氨酸-海藻酸微囊(APA微囊)的生物相容性。方法(1)两种微囊(50、100和200个)与健康人血清共浴,检测微囊对补体的激活程度。(2)1000个APA和ACP微囊分别植入Wistar大鼠的腹腔,4d和3周时统计取出的微囊数和微囊的纤维化率。(3)Wistar大鼠胰岛用ACP微囊和APA微囊包裹,分别贯续置于含3.3mmol/L和16.7mmol/L葡萄糖的Hank's溶液中培养,测定培养液中胰岛素的浓度。结果(1)ACP微囊组残余补体活性高于APA微囊组。(2)4d时,ACP和APA微囊的取出数分别是845.0±40.4和807.6±45.7(P>0.05),囊周纤维化率分别是16.40%和65.68%(P<0.05);3周时两种微囊的取出数分别为715.0±133.0和367.5±105.6(P<0.05),囊周纤维化率为27.8%和83.9%(P<0.05)。(3)在含3.3mmol/L葡萄糖的Hank's液中,未微囊胰岛组、APA和ACP微囊化胰岛组的胰岛素浓度分别是(123.48±4.70)mIU/L、(110.11±12.18)mIU/L和(110.90±11.95)mIU/L,当葡萄糖浓度为16.7mmol/L时,胰岛素浓度分别是(754.75±13.81)mIU/L、(689.30±27.71)mIU/L和(684.28±70.10)mIU/L。结论海藻酸-壳聚糖-聚乙烯乙二醇微囊的生物相容性要优于海藻酸-聚赖氨酸-海藻酸微囊,前者更适合应用于微囊化胰岛移植。     

阿司匹林壳聚糖-海藻酸钠微囊处方优化与释药机制研究

目的:制备阿司匹林壳聚糖-海藻酸钠微囊(ACSPM),并研究其处方优化与释药机制。方法:设计正交试验,以包封率为指标优化ACSPM处方并制备微囊,测定其释放度并通过释放动力学模型方程拟合探讨其释药机制。结果:所得微囊大小及含量均匀,最优处方中海藻酸钠浓度、壳聚糖浓度、海藻酸钠与阿司匹林比例分别为3.0%、1.0%、1∶4,体外释放符合Higuchi方程和Peppas方程。结论:该微囊制备工艺方法简单,释药机制以药物扩散为主兼有骨架溶蚀的non-Fickian过程。     

酮康唑微囊对部分真菌的抑菌实验

目的　考察临床分离的几种致病真菌对酮康唑微囊的体外敏感性。方法　采用试管稀释法和琼脂稀释法进行体外药效学研究。结果　 2 1株念珠菌对酮康唑、酮康唑微囊、氟康唑片的MIC分别为 0 .0 2～ 2 .5、6 .2 5～ 10 0、0 .319～ 10 0 μg·ml-1;1株酵母菌对这 3种药物的MIC分别为 0 .0 8～ 0 .16、12 .5～ 2 5、2 5 μg·ml-1结论　酮康唑微囊具有一定的体外抗真菌活性。