Microencapsulation II. Interfacial Reactions

In recent years a number of papers and patents describing the use of interfacial reactions as a means of microencapsulation have been reported in the literature. This paper discusses the technique of microencapsulation by interfacial reactions and the effect of variables which may influence the integrity of the microcapsules. Variations of the basic interfacial polymerization techniques are described with special reference to interfacial polycondensation, the formation of polymer material by induced catalyzation, vapor deposition technique, and in-situ polymerization. Examples of some processes used and/or the types of reacting species are also included.     

Microencapsulation I. Phase Separation or Coacervation

Phase separation or coacervation is one of the oldest and perhaps the most widely used method of microencapsulation. This paper discusses phase separation or coacervation as a technique of preparing microcapsules. The basic differences between simple and complex coacervation are described and the various factors which influence simple and complex coacervation are discussed. Schematic ternary phase diagrams involved in the phase separation or coacervation processes are included and the basic schemes describing the process of microencapsulation are outlined.     

微胶囊技术及其最新研究进展

综述了微胶囊技术的特点、制备方法及原理,重点对微胶囊的性能及其表征方法进行了总结,同时介绍了微胶囊的应用及其最新研究进展.     

微胶囊技术的应用及其发展

微胶囊化方法是功能性材料制备中一项重要的应用技术,近年来受到普遍关注。本文中详细地介绍了几种重要的胶囊制备方法及其在食品、渔业、医药和生物化工领域的应用实例,指出了该技术的发展前景。     

牛至精油微胶囊包埋工艺及抑菌效果的测定

目的制备牛至精油微胶囊,以提高牛至精油的稳定性。方法选取明胶和阿拉伯胶作为壁材,采用复凝聚法制备牛至精油微胶囊,并利用单因素实验和正交实验优化其工艺条件,同时研究牛至精油微胶囊的抑菌效果。结果牛至精油微胶囊化最佳的工艺条件,芯壁质量比为3︰1,反应p H值为4.5,乳化剂WJE-880的添加量为0.1%,以6000 r/min高速剪切2 min,在55℃,250 r/min的条件下搅拌固化60 min。此工艺条件下包埋率可达到83.1%。结论牛至精油经微胶囊化后显著地提高了其抑菌的持久性。     

微胶囊技术新进展

微胶囊在医药、农药、食品、化妆品、建筑、生物工程等领域具有广阔的应用前景。随着微胶囊研究的深入和应用领域的延伸,新的微胶囊技术也不断地被创造和开发。文中分别介绍了多流体复合电喷技术、超临界流体快速膨胀技术、自组装技术、多种微胶囊方法复合技术等四项制备微胶囊的新技术,并指出了微胶囊技术正向着包覆率高、功能多样、结构与性能可方便调控、制备成本低的方向发展。     

Microencapsulation by a Solvent-Free Supercritical Fluid Process: Use of Density, Calorimetric, and Size Analysis to Quantify and Qualify the Coating

Coating of microparticles or microencapsulation is a widely used operation in which a thin layer of a coating agent is deposited onto a solid particle. Currently, the technique faces two challenges: being solvent-free and being applicable for coating particles smaller than 80 microns. In this work, several techniques are used to test the feasibility of a new solvent-free coating process using supercritical fluid technology. Some model microparticles, glass beads, and an active compound (AC) are coated with Precirol®, which is a mixture of fats. The process involves two steps: first supercritical CO₂ is dissolved in molten Precirol®, then the melt solution is sprayed onto the host particles by a rapid expansion. The particles coated in this way are examined by particle size analysis, environmental scanning electron microscopy (ESEM), and IR spectrophotometry. Also mass ratios of host particle to coating are evaluated using both helium pycnometry to determine sample density and calorimetry to measure the heat of fusion of the coating agent. The results show that these analytical techniques can be used for qualitative analysis as well as quantification of the coating. Thus they give relevant information on reproducibility and feasibility of the new process.     

Microencapsulation of phosphogypsum into a sulfur polymer matrix: physico-chemical and radiological characterization

The aim of this work is to prepare a new type of phosphogypsum-sulfur polymer cements (PG-SPC) to be utilised in the manufacture of building materials. Physico-chemical and radiological characterization was performed in phosphogypsum and phosphogypsum-sulfur polymer concretes and modeling of exhalation rates has been also carried out. An optimized mixture of the materials was obtained, the solidified material with optimal mixture (sulfur/phosphogypsum = 1:0.9, phosphogypsum dosage = 10-40 wt.%) results in highest strength (54-62 MPa) and low total porosity (2.8-6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference value in the most international regulations and; therefore, these cements can be used without radiological restrictions in the manufacture of building materials. Under normal conditions of ventilation, the contribution to the expected radon indoor concentration in a standard room is below the international recommendations, so the building materials studied in this work can be applied to houses built up under normal ventilation conditions.Additionally, and taking into account that the PG is enriched in several natural radionuclides as ²²⁶Ra, the leaching experiments have demonstrated that environmental impact of the using of SPCs cements with PG is negligible.     

Methoxybutropate Microencapsulation by Gelatin-Acacia Complex Coacervation

Microcapsules of methoxybutropate solid particles or of an oily saturated solution of the same drug were prepared by complex coacervation between gelatin and acacia and dried with three different methods: isopropanol addition, spray-drying, and freeze-drying. Successively, microparticles were analyzed by infrared thermobalance, ultraviolet (UV) spectroscopy, optical and scanning electron microscopy, and sieves to find out parameters such as yield, moisture content, encapsulation percentage, morphology of solid particles, and particle size. Results highlighted that the most appropriate drying method for industrial purposes was spray-drying, particularly for oil-containing microcapsule formulations.     

Microencapsulation of Sulfadiazine with Cellulose Acetate Pethalate

Microencapsulation of a relatively insoluble drug sulfadiazine was carried out by allowing drops of' a suspension of the drug in an aqueous cellulose acetate phthalate solution to fall into an acetic acid hardening solution. Spherical microcapsules could readily be obtained when a surfactant polyoxyethylene 20 sorbitan monooleate was added to the suspensior. Increased drug concentration in the suspension yielded larger microcapsules with shorter disintegration times. The incorporation of viscosity agents into the suspension yielded microcapsules with altered disintegration times     

微囊在胶黏剂中的应用途径及表征

综述了微囊在胶黏剂行业中的应用。简述了微囊的发展、制备材料及方法,简单介绍了微囊在胶黏剂领域使用时的释放方式,重点概述了微囊在胶黏剂中应用途径的研究进展与状况,包括对基料、固化剂、溶剂等的微囊化,同时详细介绍了微囊胶黏剂的表征方法,最后对微囊在胶黏剂中的应用做了展望。     

Microencapsulation of Sulfadiazine with Cellulose Acetate Pethalate

Abstract

Microencapsulation of a relatively insoluble drug sulfadiazine was carried out by allowing drops of' a suspension of the drug in an aqueous cellulose acetate phthalate solution to fall into an acetic acid hardening solution. Spherical microcapsules could readily be obtained when a surfactant polyoxyethylene 20 sorbitan monooleate was added to the suspensior. Increased drug concentration in the suspension yielded larger microcapsules with shorter disintegration times. The incorporation of viscosity agents into the suspension yielded microcapsules with altered disintegration times     

Studies on the Microencapsulation of Dextropropoxyphene Hydrochloride. Part 1 . Preparation by Coacervation and the in Vitro Evaluation.

The main purpose of our study is to achieve the release at a slower rate and the prolonged action of dextropropoxyphene hydrochloride through microencapsulation. Besides this, microencaosulation of this active agent can prevent the incomnatibility in the presence of aspirin, and the local anesthetic effecton the tongue.

Microcapsules o f dextropropoxyphene hydrochloride (D-PRX-HCl) were prepared by coacervation method with core-shell ratios of 1:1 and 1:2, and the invitrorelease rate experiments were carried on in 0.1 N hydrochloric acid solution.     

磷系阻燃剂的微胶囊化及其在聚合物中的应用研究进展

磷系阻燃剂是阻燃效率较高的一类无卤阻燃剂,但同时存在易吸水,与基体相容性差,热稳定性不好等缺点。微胶囊化是近年来克服这些缺点的有效途径。通过分子设计不同的囊壳对阻燃剂进行微胶囊化改性,不仅可以改善阻燃剂的物理性质,还可以提高阻燃材料的阻燃性能。文中介绍了三聚氰胺-甲醛树脂、聚氨酯、环氧树脂、有机硅以及纤维素等不同囊壳材料对微胶囊化的阻燃剂及阻燃复合材料性能的影响,研究表明微胶囊化改性后的阻燃剂的耐水性、热稳定性与基体的相容性以及阻燃材料的力学性能均得到有效的提高。     

微胶囊技术在食品包装中的研究进展

目的综述微胶囊技术在食品包装领域的研究进展,为进一步开发微胶囊技术在食品包装中的应用提供科学的研究基础。方法通过对国内外研究现状和研究成果的分析和总结,介绍了微胶囊的功能、作用机理、制备和表征方法,概括了微胶囊技术在食品包装中(包括抗菌包装、防虫包装、果蔬保鲜包装、可食膜、冷鲜肉包装、相变材料-控温包装、生物质包装材料)的研究进展。结果分析表明微胶囊技术能够增加活性成分的稳定性,与包装系统结合能够达到缓释抗菌或控制温度等效果,提高了产品的货架期,其与包装系统的结合主要有4种方法(原料共混、涂覆、装入小袋置于包装系统、固载纤维法)。结论研究微胶囊与聚合物原料的最佳加入比例能够获得综合性能较好的包装膜,微胶囊技术在可食膜、相变材料-控温包装、生物质包装材料方面的发展潜力较大。     

Studies on the Microencapsulation of Dextropropoxyphene Hydrochloride. Part 2. Tee in vivo Urinary Excretion in Man.

Abstract

I this study, the spectrophotometric method suggested by Amundson et al (1) was used for the quantitation of dextropropoxyphene hydrochloride (D-PRX.HCL) (free drug plus metabolite) in urine after the oral administration of powder drug and microcaosules.     

Studies on the Microencapsulation of Dextropropoxyphene Hydrochloride. Part 2. Tee in vivo Urinary Excretion in Man.

I this study, the spectrophotometric method suggested by Amundson et al (1) was used for the quantitation of dextropropoxyphene hydrochloride (D-PRX.HCL) (free drug plus metabolite) in urine after the oral administration of powder drug and microcaosules.