Polymethylmethacrylate Coated Alginate Matrix Microcapsules for Controlled Release of Diclofenac Sodium

Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape;however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.

Culture of yeast cells immobilized by alginate-chitosan microcapsules in aqueous-organic solvent biphasic system

Immobilization biocatalysis is a potential technology to improve the activity and stability of biocatalysts in nonaqueous systems for efficient industrial production.Alginate-chitosan(AC)microcapsules were prepared as immobilization carriers by emulsifi cation-internal gelation and complexation reaction,and their contribution on facilitating the growth and metabolism of yeast cells were testifi ed successfully in culture medium-solvent biphasic systems.The cell growth in AC microcapsules is superior to that in alginate beads,and the cells in both immobilization carriers maintain much higher activity than free cells,which demonstrates AC microcapsules can confer yeast cells the ability to resist the adverse effect of solvent.Moreover,the performance of AC microcapsules in biphasic systems could be improved by adjusting the formation of outer polyelectrolyte complex(PEC)membrane to promote the cell growth and metabolic ability under the balance of resisting solvent toxicity and permitting substrate diffusion.Therefore,these findings are quite valuable for applying AC microcapsules as novel immobilization carriers to realize the biotransformation of value-added products in aqueous-solvent biphasic systems.

Selective Separation of Au（lll） by the Column of Alginate Xerogel Microcapsules Enclosing TOA Extractant

The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA microcapsules （TOA-MCs） were examined using DM, SEM/EDS and EPMA. The adsorption and elution properties of Au（III） were studied by the column method using spherical and highly porous TOA-MCs. The uptake properties of precious metals （Au（IIl）, Pt（IV）, and Pd（II）） were examined by the batch method using TOA-MCs in different concentrations of hydrochloric acid （HCI） solution. The order of uptake （%） of the precious metals was Au（III） 〉 Pt（IV） 〉 Pd（II）. TOA-MCs have strong affinity towards Au（III） in HCI solution. The uptake （%） of Au（III） by TOA-MCs was estimated to be -100% and equilibrium was attained within 1 hour. The breakthrough and elution behaviors of Au（III） were examined by varying the Au（III） concentration in the feed, flow rate, reaction temperature, and eluent concentration. The Au（IlI） in 1 M HCI solution was effectively extracted with TOA-MCs in the column operation. The breakthrough curve showed the S-shaped profile and no dislodgement of TOA from the matrices of CaALG. The breakthrough curve rose steeply and the uptake of Au（IIl） was fairly fast, which indicated a relatively high uptake rate of Au（III） in TOA-MCs. The break point （5% breakthrough） and breakthrough capacity （B. T. Capacity） were estimated to be 82 cm3 and 0.60 mmol/g, respectively. The total capacity （T. capacity） was estimated to be 1.30 mmol/g, which was considerably larger than those of conventional resins. The elution properties of Au（Ill） were studied by varying the concentration of thiourea （0.025 M-1 M） in 1 M HC1 solution. The retention volume （VR, cm3） tended to decrease with the increase in thiourea （TU） concentration. The loaded Au（III） ions were successfully eluted （- 100%, total elution percentage） by the eluent of TU （0.5 M） in HC1 （1 M） solution. The alginate gel microcapsules enclosing TOA extractant were thus effective for the selective separation and recovery of Au（IIl） ions in HCI solution.

Intraperitoneal distribution of alginate microcapsules in mice

Introduction: Improved drug delivery mechanisms for the treatment of residual peritoneal cancer cells following cytoreduction surgery are needed. Alginate microcapsules are a potentially useful mechanism for delivery of bioengineered cells, but when injected into the peritoneum, their distribution and properties are not well described. Methods: Aliquots of 300, 600 or 1200 microcapsules were injected into the peritoneum of 81 mice. Mice were sacrificed at 6, 12, 18, and 48 days and laparotomy was performed to quantify the distribution of microspheres. Results: The injections were well tolerated for up to 48 days. No peritoneal adherence or inflammatory reaction was noted to the microcapsules. Injection of 1200 microcapsules resulted in a better overall persistence and widespread peritoneal distribution at up to 48 days. The volume of fluid used for injection of the microcapsules did not affect their distribution or persistence. Conclusion: The intraperitoneal injection of alginate microspheres allows wide and persistent distribution throughout the abdominal cavity. The next step is to test the distribution of microcapsules when delivered following surgery in a rodent model.

Effect of Sodium Alginate Concentration on Membrane Strength and Permeating Property of Poly-l-arginine Group Microcapsule

A novel poly-/-arginine microcapsule was prepared due to its nutritional function and pharmacological efficacy. A high-voltage electrostatic droplet generator was used to make uniform microcapsules. The results show that the membrane strength and permeating property are both remarkably affected with the changes of sodium alginate concentration. With the sodium alginate concentration increasing, gel beads sizes increase from 233μm to 350μm, release ratio is also higher at the same time, but the membrane strength decreases.

Leydig Cells Encapsulation with Alginate-Chitosan: Optimization of Microcapsule Formation

This research aimed to optimize the formation of microcapsules from alginate and chitosan for Leydig cells encapsulation. Alginate was used as the first coating agent while chitosan was the second layer. Various concentrations of alginate and CaCl2 were applied utilizing the extrusion method and the best concentration was determined based on their formation time, shape and diameter of microcapsules. Alginate microcapsule was applied with chitosan in various con- centrations. The best chitosan concentration was selected based on its mechanical stability. The results showed that the minimum concentration of alginate was 1.5% (w/v) with viscosity of 33.8 cPs, resulted to spherical microcapsules with diameters of 230 - 270 μm. The optimum concentration of chitosan as the second coating agent was 0.5% (w/v), resulted to spherical microcapsules with mechanical stability of 4 hours. Leydig cells were trapped inside the microcapsule with a density that is proportional to the concentration of cells used in the encapsulation.

Formulation and evaluation of Albendazole microcapsules for colon delivery using chitosan

Objective:To formulate and evaluate Albendazole microcapsules using chitosan,a natural polymer for colon-specific delivery for better treatment of helminthiasis,filariasis,colorectal cancer,avoiding the side effects.Methods:The Albendazole microcapsules were prepared by the use of different concentrations of sodium alginate,chitosan and hydroxypropyl methylcellulose(HPMC).The polysaccharides chitosan reacted with sodium alginate in the presence of calcium chloride to form microcapsules with a polyelectrolyte complex membrane by electrostatic interactions between the two oppositely charged polymers.The microcapsules were then studied for entrapment efficiency,drug-polymer compatibility and surface morphology. In vitro drug release study in presence and absence of cecal content were also studied.Further, kinetic modellings were employed to find out release mechanisms.Results:Albendazole loaded microspheres showd high entrapment efficiency(72.8%) and the microcapsules were free flowing,non aggregated and spherical,between 600 and 1 000μm in diameter.The surface of microcapsules were found to be porous and wavy.The FT-IR spectrum showed that there is no interaction between the polymer and the drug.The in vitro drug release study found to be affected by change in chitosan,sodium alginate and HPMC concentration.The microcapsules with 2.5% sodium alginate and 0.4% chitosan shown minimum release in gastrointestinal simulated condition but shows maximum drug release at the end of 24th hour in presence of cecal content.The rate of drug release follows Korsmeyer-peppas model that was the drug release is by diffusion and erosion.Conclusions:The study reveals that Albendazole loaded chitosanalginate based microsphere can be used effectively for the colon targeting.

Amphiphilic sodium alginate-vinyl acetate microparticles for drug delivery

To overcome the fast or burst release of hydrophilic drugs from hydrophilic alginate-based carriers,hydrophobic molecule(vinyl acetate,VAc)was grafted on alginate(Alg),which was further used to prepare drug carriers.Amphiphilic Alg-g-PVAc hydrogel beads were firstly prepared by emulsification/internal gelation technique for the loading of bovine serum albumin(BSA).Then,chitosan was coated on the surface of beads to form novel amphiphilic Alg-g-PVAc/chitosan(Alg-g-PVAc/CS)microcapsules.The BSA-loading amphiphilic Alg-g-PVAc/chitosan(Alg-g-PVAc/CS)microcapsules display similar morphology and size to the hydrophilic alginate/chitosan(AC)microcapsules.However,the drug loading and loading efficiency of BSA in Alg-g-PVAc/CS microcapsules are higher,and the release rate of BSA from Alg-g-PVAc/CS microcapsules is slower.The results demonstrate that the introduction of hydrophobic PVAc on alginate can effectively help retard the release of BSA,and the higher degree of substitution is,the slower the release rate is.In addition,the complex membrane can also be adjusted to delay the release of BSA.As a whole,amphiphilic sodium alginate-vinyl acetate/CS microparticles could be developed for macromolecular drug delivery.

Diffusion Characteristics in Microcapsules

An equation of diffusion for microcapsules（hollow sphere）was developed,employing the mathematicalmodel for the diffusion characteristics of solid sphere.In the proposed equation,a combination diffusion coeffi-cient was introduced as a substitute for the diffusion coefficient in the solid sphere mathematical model and ex-pressed as a function of the diffusion coefficient inside solution of hollow sphere,as well as in the polymer mem-brane.With this modified model,the diffusion coefficients of glucose in NaCS（sodium cellulose sulfate）-PDADMAC（Poly-diallyl-dimethyl-ammonium chloride）membrane and in Ca-alginate gel membrane were deter-mined.The diffusion coefficient in NaCS-PDADMAC membrane was found to be 2.12×10-11m2·s-1and thatin Ca-alginate membrane 2.62×10-10m2·s-1.

Transferring Process of RE^(3+) with the Microcapsules Containing P507

thylhexyl phosphonic acid mono-2-ethylhexyl ester (P507) was microencapsulated with ethyl cellulose and calcium alginate respectively.The microcapsules containing P507 can be used to extract and enrich Lu3+,Nd3+,and La3+ from aqueous solutions into them.Because of the immobility of the wall to the extractive agent,it changes the processes that the ions transfer into the agent (core material).Their relative transferring rates can be compared in accordance with permeative coefficiencies.The permeative coefficiencies will vary as the pH of the aqueous solutions is changed.Therefore,the differences of them between two ions can be enlarged in this way.The REP-507 complex can be stripped with 6 mol·L-1 HCl,which should enrich the ions quantitatively.

Study on adsorption behavior of cesium using ammonium tungstophosphate(AWP)-calcium alginate microcapsules

A functional microcapsule was prepared by encapsulating the fine crystalline ammonium tungstophosphate （AWP） in calcium alginate polymer （CaALG）. The characterization of AWP-CaALG microcapsule was examined by SEM and EPMA. The ad- sorption behavior of Cs（Ⅰ）, Rb（Ⅰ）, Sr（Ⅱ）, Pd（II）, Ru（Ⅲ）, Rh（Ⅲ）, La（Ⅲ）, Ce（Ⅲ）, Dy（Ⅲ） and Zr（IV） was investigated by the batch method. The batch experiments were carried out by varying the shaking times, HNO3 concentration, and initial concen- tration of metal ions. Relatively large K＋ values above 105 cm3/g for Cs（I） were obtained in the range of 0.1-5 M HNO3, re- sulting in a separation factor of Cs/Rb exceeding 102. In contrast, the K＋ values of Sr（II）, Pd（II）, Ru（Ⅲ）, La（Ⅲ）, Dy（Ⅲ）, Ce（Ⅲ） and Zr（IV） were considerably lower than 50 cm3/g. The K＋ value of Cs（1） decreased in the order of the coexisting ions, H＋ 〉 Na＋ 〉〉 NH4＋, and a linear relationship with a slop of about -1 was obtained between log Kd and log [NH4＋] （[NH4＋] 〉 0.01 M） The adsorption of Cs（I） was found to be controlled by chemisorption mechanism, and followed a Langmuir-type adsorption equation. A high uptake percentage of 99.4% for Cs（I） was obtained by using the dissolved solutions of spent fuel from FBR-JOYO （JAEA）.

研究型分析化学综合实验教学模式探究——以“海藻酸盐微胶囊的制备、药物包封及缓控释分析实验”为例

“海藻酸盐微胶囊的制备、药物包封及缓控释分析实验”是II型分析化学实验中非常典型的一个研究型实验,它涵盖了微胶囊形成原理探究、实验条件设计、微胶囊性能表征等科研基本能力的训练。将海藻酸钠与亚甲基蓝混合溶液分别滴加至3%CaCl2溶液和1%壳聚糖溶液中,从而制备出两种不同性能的微胶囊。通过分光光度法测得不同时间溶液的浓度,从而得到缓释曲线,并对两种胶囊的缓释性进行对比分析。后续探究实验采用一步法和两步法制备微胶囊,将两种体系的优点结合起来,得到缓释性和稳定性均较好的微胶囊。

宽叶独行菜提取物微胶囊的制备与表征

利用微胶囊技术,以宽叶独行菜提取物为芯材、海藻酸钠为壁材,制备宽叶独行菜提取物微胶囊,设计响应面实验并对其性能进行表征.结果表明,宽叶独行菜提取物微胶囊最佳制备方案为:海藻酸钠质量浓度为2.0%,氯化钙质量浓度2.0%,芯壁体积比1∶3.从扫描电子显微镜成像图片可以看出,微胶囊整体呈球状,形状规则,结构紧致,成形性好.FTIR和TG图谱显示宽叶独行菜提取物被很好地包裹在壁材里,且具有良好的热稳定性.最后对微胶囊进行体外胃肠液模拟消化实验,12h后肠液和胃液累积释放量分别达到80.21%和24.32%.微胶囊在胃肠液中的释放动力学拟合结果表明,零级拟合方程更能反映体外释放行为.

Sono-assembly of folate-decorated curcumins/alginate core-shell microcomplex and its targeted delivery and pH/reduction dual-triggered release

In this study,sodium alginate(SA),a non-toxic natural polysaccharide with good biocompatibility and biodegradability,was developed for targeted delivery of curcumin(CUR)in tumor therapy.The strategy is to sulfhydrylate the folic acid(FA)modified SA,and the CUR dissolved in ethyl acetate(EAC)phase is coated in microcapsules by a quick,efficient and environment-friendly sonochemical method.The EAC in the microcapsule core is volatile,which can be recycled and reused to reduce cost.The prepared mi-crocapsules(FA-RSMCs@CUR)exhibited similar toxicity to free curcumin in anti-tumour evaluation in vitro.FA-RSMCs@CUR also exhibited effective antibacterial properties in the antibacterial evaluation in vitro.It is expected to become a low-cost tumor targeting vector in the future,and has the potential to be promoted in clinical application.

Eudragit RS 30D修饰的冰片缓释微囊的制备与评价

目的筛选制备海藻酸钠-丙烯酸树脂冰片微囊(SA/RS 30D/BN MCs)的最佳工艺,并对微囊进行相关表征。方法采用复凝聚法制备SA/RS 30D/BN MCs,以包封率和载药量为考察指标,采用单因素法考察冰片、可溶性淀粉、Tween 80、海藻酸钠(SA)溶液、Eudragit RS 30D和CaCl2溶液的质量浓度对微囊质量的影响;在此基础上,以包封率为考察指标,通过L(934)正交试验筛选最佳处方,并对微囊的外观形态、理化性质、体外释放情况及初步稳定性进行评价。结果SA/RS 30D/BN MCs最佳处方为:冰片、可溶性淀粉、Tween 80、SA溶液、Eudragit RS 30D、CaCl2溶液的质量浓度分别为3.33%、0.17%、0.17%、1.00%、5.00%、1.50%,微囊的平均包封率为(94.18±0.47)%,平均载药量为(30.42±0.17)%,在初步稳定性试验中微囊中冰片保留率高达92.2%,表征结果表明成功制备了具有缓释性能的冰片微囊。结论采用复凝聚法以海藻酸钠、Eudragit RS 30D为复合囊材制备的冰片微囊可以显著提高冰片的稳定性且具有一定的缓释效果。

聚合物微胶囊中再生剂对沥青胶浆自修复性能的影响研究

研究了葵花籽油海藻酸钙微胶囊在沥青胶浆中的自修复效果。通过对微胶囊形态、物理、热学和力学性能进行评价,并考察了微胶囊油含量以及自修复温度对沥青胶浆自修复性能的影响。实验结果表明,微胶囊能够在混合和压实过程中保持完整,在沥青胶浆遭受机械载荷导致裂缝时释放出油,有效实现自我修复。含有微胶囊的沥青胶浆样品显示出更高水平的自修复能力,这与无微胶囊样品相比有显著差异。微胶囊的含油量和温度是影响自修复水平的关键因素。

载细胞海藻酸钠/壳聚糖微胶囊的化学破囊方法研究

以海藻酸钠 -壳聚糖 -海藻酸钠微胶囊 (简称 ACA微胶囊 )为研究体系 ,建立了一种生理条件下 ACA微胶囊的化学破囊方法 ,破囊过程充分考虑了对囊内生物物质活性的保持 .以微生物细胞 Pichia pastorisGS1 1 5和动物细胞 L92 9为模型 ,以 Na HCO3和 Na3C6 H5O7· 2 H2 O为破囊液基本组分 ,考察了破囊液对ACA微胶囊的破囊效果及破囊过程对囊内细胞活性的影响 .结果表明 ,破囊操作可在 3 0 s内完成 ,破囊率为 1 0 0 % ,微胶囊膜完全溶解 ,破囊后细胞存活率在 85

海藻酸钠-壳聚糖微胶囊膜强度的研究

以乳化 /内部凝胶化法制备了海藻酸钠 -壳聚糖微胶囊 ,重点考察了成膜反应过程中影响微胶囊膜强度的几个主要参数 ,实验发现 ,壳聚糖分子量低于 1 0 0 0 0 0 ,成膜反应时间高于 1 5 min,壳聚糖溶液 p H值在6.0左右时制备的微胶囊膜强度较高 .初步探讨了海藻酸钠与壳聚糖两种高分子发生聚电解质络合反应的机制 .