纺丝原液原位合成相变材料微胶囊制备石蜡/PVA储能纤维

以聚乙烯醇(PVA)纺丝原液为分散介质, 常温相变材料RT27石蜡为芯材, 正硅酸乙酯(TEOS)为聚合单体形成SiO₂囊壳, 通过原位聚合直接制备含有石蜡微胶囊的PVA纺丝原液, 之后通过湿法纺丝制备石蜡/PVA储能纤维。通过正交实验优化, 结合粒径分布软件, 分析各因素对微胶囊粒径的影响, 选择适合纺丝的微胶囊合成条件。采用FTIR-ATR、SEM、EDS及TEM表征了纤维及微胶囊的化学成分及形态, 通过DSC、TGA表征了微胶囊的包覆率、纤维的储能性及热稳定性。结果表明: PVA纺丝原液中合成了SiO₂凝胶包裹的相变微胶囊, 其平均粒径为1.39 μm, 大小及分布适合纺丝。纤维相变焓值为45.39 J/g, 石蜡包裹率高达94.72%, 纺出纤维具有较高的储能性和较好的热稳定性。     

Investigation of the effect of various shellac coating compositions containing different water-soluble polymers on in vitro drug release

In this study drug pellets were coated with aqueous shellac coating formulations containing different amounts of polyvinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC), and carbomer 940. The coating level needed for enteric coating was determined. The influence of different amounts of PVA, HPMC, and carbomer on drug release and mechanism; the porosity, and the stability of shellac coatings was investigated. The results show that the incorporation of different concentrations of HPMC into shellac coatings, due to the increasing of pores, could considerably increase the drug release from the pellets in purified water. Moreover, the swelling effect of carbomer 940 leads to much more diffusivity through shellac coatings in water. In addition, PVA results in small cracking in the films and much more diffusion of drug in water. Furthermore, all coating systems containing different hydrophilic polymers that were used in the present work could prevent the dissolution of drug in simulated gastric juice for 2 hours. On the other hand, a rapid and complete release of drug within 45 minutes was observed in simulated intestinal fluid. Drug release from shellac coated pellets and ones containing different amounts of carbomer was affected between 3-6 months, whereas shellac coatings containing different amounts of PVA or HPMC show the same dissolution profiles with small deviation after 12 months.     

Preparation of Acetaminophen Microcapsules by Coaservation-Phase Separation Method

In this study, it was aimed to prepare prolonged action microcapsules of acetaminophen with short biological half-life by a non-solvent addition method which is one of the conservation-phase separation techniques.

For this purpose, the three different particle size ranges of acetaminophen (0.088-0.177 mn, 0.250-0.354 mn, 0.420-0.500 mn) were used. The solution of polyisobuthylene in cyclohexane as a non-solvent and Eudragit RS and Eudragit RL as coating polymers were also used. The prepared mi crosapsules were compressed by a hydraulic press using different types of direct tableting agents such as Ludipress, Avicel PH 101 and Lactose EP D 30. Dissolution rates of each tablet containing 160 mg of microencapsulated acetaminophen were examined by continuous flow-through cell method

The results of this study showed that the release rate of drug from microcapsules prepared with Eudragit RS was lower than that of microcapsules prepared with Eudragit RL. However different particle size ranges of drug didn't affect significantly the release rate; but different types of direct tableting agents were effective on the release rate of drug.     

Production of a Coacervate Film for Microcapsule Diffusion Studies

Until the last five years, study of microcapsules formed by complex coacervation has been approached almost entirely on an empirical basis. The gelatin-acacia coating formed through complex coacervation is responsible for the sustained release characteristics of the dosage form. Because dissolution of the drug from microcapsules is often limited by the structure and nature of the shell wall, of prime interest would be the construction of an acacia-gelatin film for diffusion studies. Apparent optimal conditions for production of the coacervate film were developed. The conditions were similar to those used to produce microcapsules by various researchers. These conditions produced a coacervate film which could be cut into two square centimeter sections apparently suitable for diffusion studies. Films produced by complex coacervation appeared free from structural defects when observed with a stereo-microscope.     

Preparation of Oil-Encapsulated Microcapsules and Tribological Property of Ni Composite Coating

Microcapsules containing oil are potential candidate materials for preparing electrocomposite coatings with excellent tribological properties. In the present study, the preparation of oil-encapsulated microcapsules and electrodeposition of Ni-microcapsule composite coating are presented along with the properties of the coating. In situ interfacial polymerization method was used for the preparation of lubricating oil-encapsulated urea-formaldehyde microcapsules. The synthesized microcapsules were incorporated into the nickel matrix by electrodeposition using Ni-Watts bath. The Ni-composite coating containing microcapsules exhibited smaller Ni grain size, higher microhardness and lower surface roughness compared to plain Ni coating. Electrodeposited Ni coating containing oil-encapsulated microcapsules exhibited improved tribological properties with lower wear loss and coefficient of friction compared to plain nickel coating.     

Microencapsulation of Ibuprofen by A Coacervation Process Using Eudragit L100-55 as An Enteric Polymer

Ibuprofen microcapsules were prepared using Eudragit as enteric coating material and a simple coacervation method as coating process. Preliminary experiments based on results published with cellulose acetate phthalate led to the formation of a precipitate rather than a coacervate. Adjusting the polarity of the solvent in the Eudragit system by the addition of cosolvents enabled the transformation of the precipitate into a coacervate. This behaviour was qualitatively explained using the solubility parameter approach. The coacervate phase obtained from a system containing 2-propanol as cosolvent was assayed quantitatively in the absence and in the presence of ibuprofen. Due to the increased solubility of the drug in the cosolvent containing system, the composition of the coacervate phase was significantly altered when compared to a system without drug. The surface morphology of the microcapsules was assessed by scanning electron microscopy. The enteric properties of the microcapsules were tested according to the USP XXII test procedures. The permeability of the wall was evaluated by a dissolution test performed at pH 4. During stability testing over a period of 6 months the quality of the ibuprofen microcapsules remained almost unchanged.     

Microencapsulation of Ibuprofen by A Coacervation Process Using Eudragit L100–55 as An Enteric Polymer

Abstract

Ibuprofen microcapsules were prepared using Eudragit as enteric coating material and a simple coacervation method as coating process. Preliminary experiments based on results published with cellulose acetate phthalate led to the formation of a precipitate rather than a coacervate. Adjusting the polarity of the solvent in the Eudragit system by the addition of cosolvents enabled the transformation of the precipitate into a coacervate. This behaviour was qualitatively explained using the solubility parameter approach. The coacervate phase obtained from a system containing 2-propanol as cosolvent was assayed quantitatively in the absence and in the presence of ibuprofen. Due to the increased solubility of the drug in the cosolvent containing system, the composition of the coacervate phase was significantly altered when compared to a system without drug. The surface morphology of the microcapsules was assessed by scanning electron microscopy. The enteric properties of the microcapsules were tested according to the USP XXII test procedures. The permeability of the wall was evaluated by a dissolution test performed at pH 4. During stability testing over a period of 6 months the quality of the ibuprofen microcapsules remained almost unchanged.     

Controllable Fabrication of Inhomogeneous Microcapsules for Triggered Release by Osmotic Pressure

Inhomogeneous microcapsules that can encapsulate various cargo for controlled release triggered by osmotic shock are designed and reported. The microcapsules are fabricated using a microfluidic approach and the inhomogeneity of shell thickness in the microcapsules can be controlled by tuning the flow rate ratio of the middle phase to the inner phase. This study demonstrates the swelling of these inhomogeneous microcapsules begins at the thinnest part of shell and eventually leads to rupture at the weak spot with a low osmotic pressure. Systematic studies indicate the rupture fraction of these microcapsules increases with increasing inhomogeneity, while the rupture osmotic pressure decreases linearly with increasing inhomogeneity. The inhomogeneous microcapsules are demonstrated to be impermeable to small probe molecules, which enables long‐term storage. Thus, these microcapsules can be used for long‐term storage of enzymes, which can be controllably released through osmotic shock without impairing their biological activity. The study provides a new approach to design effective carriers to encapsulate biomolecules and release them on‐demand upon applying osmotic shock.     

PBAT/PVA复合涂布膜阻隔性研究

目的 为改善PBAT膜的阻隔性,通过以戊二酸为交联剂改性PVA制备涂膜液,利用涂布法制备了具有高阻隔性的PBAT/PVA复合薄膜。方法 采用红外光谱、差示扫描量热仪、接触角测试仪、水蒸气透过率测试仪等对改性PVA单膜、PBAT/PVA复合膜的结构和性能进行研究。结果 表明由于戊二酸与PVA之间有一定的酯化作用,消耗PVA中部分羟基,从而提高了PVA的耐水性。戊二酸改性提高了PVA膜的疏水性,其接触角从11.3°提高到60.6°。与PBAT纯膜相比,涂覆了戊二酸的PVA涂膜液改性3 h后复合膜水蒸气透过率由647.95 g/(m²·24 h)降低到132.07 g/(m²·24 h)、氧气透过量由17 730.3 cm³/(m²·d·MPa)降低到396.6 cm³/(m²·d·MPa),证明改性3 h的PVA涂膜液对增加PBAT阻隔性最有帮助。结论 利用涂布法制备的PBAT/PVA复合薄膜具有较高阻隔性,为PBAT的广泛应用打下了基础。     

Electrodeposition of composite copper/liquid-containing microcapsule coatings

This paper presents results on the preparation of microcapsules containing liquid organosilica, and their co-deposition with copper in an acidic copper electrolyte onto a carbon steel cathode to form a copper/microcapsule composite coating. Microscopic analyses of the surface and the cross-section of the coating confirm the incorporation of the liquid-containing microcapsules in the coating layer. The influence of microcapsules in the electrolyte on the cathode polarization, as well as that of process conditions on the microcapsule inclusion, is also discussed.     

Design and characterization of enteric-coated controlled release mucoadhesive microcapsules of Rabeprazole sodium

The objectives of present work was to design and characterize the rabeprazole sodium loaded microcapsules prepared by solvent evaporation technique using ethyl cellulose (EC) based various mucoadhesive polymer, followed by a triple coating with Eudragit L100. The Box-behnken design (BBD) was applied for optimization of formulations containing EC, HPMCK100M and Eudragit L100 as factors for selected responses like entrapment efficiency, mucoadhesive property and drug release in 24 h. The prepared microcapsules were characterized for particle size, drug content, swelling index, mucoadhesive strength, and in vivo antiulcer activity. FT-IR studies revealed that there was no drug-polymer interaction. SEM studies revealed that microcapsules were non-aggregated, spherical shape and smooth appearance. In vitro drug release data from microcapsules was fitted to different kinetic models to explain release profiles. The correlation coefficient value (r²) indicated that the drug release followed Higuchi model. Analysis of variance (ANOVA) showed significant difference in the release of drug from all formulations at p < 0.05 level. Accelerated stability study of optimized formulation (F4) upto 6 months showed there was no change in drug content and release characteristics during storage. In vivo antiulcer activity showed that the optimized microcapsules were able to protect rat stomach against ulcer formation vis-à-vis aqueous solution of the drug showed only negligible and minimum effect.     

Drug Release Properties of the Microcapsules of Adriamycin Hydrochloride with Ethylcellulose Prepared by a Phase Separation Technique

Adriamycin hydrochloride was microencapsulated with ethylcellulose by a phase separation method to develop a prolonged release dosage form. Polyisobutylene (PIB) was used as a coacervation-inducing agent to control the particle size and drug release rate of the resultant microcapsules. With increasing the concentration of PIB (1 to 3 %) the average diameter of the microcapsules decreased, due to the fact that the microcapsules were discreted to a single microcapsule. At low concentration of PIB, the resultant microcapsules were agglomerated, which resulted in increasing the size. The microcapsules prepared with PIB 2 % prolonged desirably the drug release from the microcapsules. A little size effects of the microcapsules on the drug release rate was found for the microcapsules with PIB 2 % and 3 %.     

Robust Microcapsules with Controlled Permeability from Silk Fibroin Reinforced with Graphene Oxide

Robust and stable microcapsules are assembled from poly‐amino acid‐modified silk fibroin reinforced with graphene oxide flakes using layer‐by‐layer (LbL) assembly, based on biocompatible natural protein and carbon nanosheets. The composite microcapsules are extremely stable in acidic (pH 2.0) and basic (pH 11.5) conditions, accompanied with pH‐triggered permeability, which facilitates the controllable encapsulation and release of macromolecules. Furthermore, the graphene oxide incorporated into ultrathin LbL shells induces greatly reinforced mechanical properties, with an elastic modulus which is two orders of magnitude higher than the typical values of original silk LbL shells and shows a significant, three‐fold reduction in pore size. Such strong nanocomposite microcapsules can provide solid protection of encapsulated cargo under harsh conditions, indicating a promising candidate with controllable loading/unloading for drug delivery, reinforcement, and bioengineering applications.     

Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe₃O₄), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.     

Drug Release Properties of the Microcapsules of Adriamycin Hydrochloride with Ethylcellulose Prepared by a Phase Separation Technique

Abstract

Adriamycin hydrochloride was microencapsulated with ethylcellulose by a phase separation method to develop a prolonged release dosage form. Polyisobutylene (PIB) was used as a coacervation-inducing agent to control the particle size and drug release rate of the resultant microcapsules. With increasing the concentration of PIB (1 to 3 %) the average diameter of the microcapsules decreased, due to the fact that the microcapsules were discreted to a single microcapsule. At low concentration of PIB, the resultant microcapsules were agglomerated, which resulted in increasing the size. The microcapsules prepared with PIB 2 % prolonged desirably the drug release from the microcapsules. A little size effects of the microcapsules on the drug release rate was found for the microcapsules with PIB 2 % and 3 %.     

Preparation and Characterization of Ethylcellulose-Walled Theophylline Microcapsules Using the Emulsion-Solvent Evaporation Technique

Ethylcellulose microcapsules containing theophylline are prepared by emulsification of a organic ethylcellulose solution in a oil phase containing a surfactant. The preparation is based on dispersion of acetone containing the drug in liquid paraffin. Tween 80 was used as a dispersing agent. Good reproducibility in microcapsule preparation was observed. The microcapsules obtained were uniform and free-flowing particles. The type of the stirring-manner (propella - and magnet - stirring), and the drug to polymer ratios have an important influence on the in vitro dissolution and release of theophylline from microcapsules.     

壳聚糖/PHB复合缓释微包囊的制备与体外释药评价

用疏水性聚酯PHB外包覆壳聚糖-三聚磷酸钠-阿斯匹林药物缓释体(CPA)制备了壳聚糖/PHB复合缓释微包囊(CPAB),以克服CPA遇酸不稳定的释药特点.用傅立叶红外分光光度计、激光粒度仪、扫描电镜表征了CPAB的组成、粒径及表面形貌.结果显示,CPAB粒径在50～100nm和载药率18.5%时,表面有不均匀的空隙.体外释药评价证实CPAB能有效解决CPA在酸性下的不稳定性,具有长效缓释作用.     

Characterization of multilayer anti-fog coatings

Fog formation on transparent substrates constitutes a major challenge in several optical applications requiring excellent light transmission characteristics. Anti-fog coatings are hydrophilic, enabling water to spread uniformly on the surface rather than form dispersed droplets. Despite the development of several anti-fog coating strategies, the long-term stability, adherence to the underlying substrate, and resistance to cleaning procedures are not yet optimal. We report on a polymer-based anti-fog coating covalently grafted onto glass surfaces by means of a multistep process. Glass substrates were first activated by plasma functionalization to provide amino groups on the surface, resulting in the subsequent covalent bonding of the polymeric layers. The anti-fog coating was then created by the successive spin coating of (poly(ethylene-maleic anhydride) (PEMA) and poly(vinyl alcohol) (PVA) layers. PEMA acted as an interface by covalently reacting with both the glass surface amino functionalities and the PVA hydroxyl groups, while PVA added the necessary surface hydrophilicity to provide anti-fog properties. Each step of the procedure was monitored by XPS, which confirmed the successful grafting of the coating. Coating thickness was evaluated by profilometry, nanoindentation, and UV visible light transmission. The hydrophilic nature of the anti-fog coating was assessed by water contact angle (CA), and its anti-fog efficiency was determined visually and tested quantitatively for the first time using an ASTM standard protocol. Results show that the PEMA/PVA coating not only delayed the initial period required for fog formation but also decreased the rate of light transmission decay. Finally, following a 24 hour immersion in water, these PEMA/PVA coatings remained stable and preserved their anti-fog properties.     

Poly(vinyl alcohol) hydrogels as hydrophilic matrices for the release of lipophilic drugs loaded in PLGA nanoparticles

Poly(vinyl alcohol) (PVA) hydrogels prepared by a freeze-thawing procedure were evaluated as matrices for the release of water-insoluble drugs such as dexamethasone. As it is impossible to directly entrap a lipophilic drug into a hydrophilic matrix, a novel mechanism has been designed based on producing biodegradable nanoparticles loaded with the drug, that could then be entrapped into the hydrogels. Nanoparticles were prepared by a solvent evaporation technique using a biodegradable copolymer of poly(lactic acid)-poly(glycolic acid) (PLGA). The effects of several processing parameters on particle properties were investigated. The drug release from free nanoparticles was compared to that from the nanoparticles entrapped into the PVA matrices. It was observed that the release profile of the drug is not significantly affected by the PVA matrix. A correlation was found between the amount of drug released and the PVA concentration in the hydrogels: the percentage of drug released, as a function of time, decreased by increasing PVA concentration, indicating that PVA concentration can be used as a tool in modulating the release of the drug.     

微胶囊相变材料的储能特性分析

以硬脂酸丁酯为囊芯,密胺树脂(MF)和聚酯树脂(PET)为囊壁,合成了两种具有相变储热功能的胶囊.采用扫描电子显微镜(SEM)观察胶囊的形貌,差示扫描量热仪(DSC)研究胶囊的储热性能,发现MF/硬脂酸丁酯微胶囊表面粗糙,储能效果明显,稳定性好.利用MF/硬脂酸丁酯微胶囊制备了具有相变储能功能的建筑材料,微胶囊在水泥和...