Solubility of Core Materials in Aqueous Polymeric Solution Effect on Microencapsulation of Curcumin

Curcumin, the main active constituent of turmeric herb (Curcuma longa L.) have been reported to possess many medicinal values. The application of curcumin in dermatological preparations is limited by their intense yellow color property, which stains the fabric and skin. The objectives of this study were to reduce the color staining effect and enhance the stability of curcumin via microencapsulation using gelatin simple coacervation method. As for curcumin, ethanol and acetone were used as coacervating solvents. Curcumin was dispersed in ethanol while dissolved in acetone. Irrespective of the types of coacervating solvents used, microencapsulation resolved the color-staining problem and enhanced the flow properties and photo-stability of curcumin. Nevertheless, it was found that more spherical curcumin microcapsules with higher yield, higher curcumin loading, and higher entrapment efficiency were obtained with acetone than ethanol. The in vitro release of curcumin after microencapsulation was slightly prolonged. Further evaluation of the effects of solubility of core materials in coacervating solvent or polymeric aqueous solution using six different drug compounds, namely, ketoconazole, ketoprofen, magnesium stearate, pseudoephedrine HCl, diclofenac sodium, and paracetamol, suggested that the solubility of core materials in aqueous polymeric solution determined the successful formation of microcapsules. Microcapsules could only be formed if the core materials were not dissolved in the aqueous polymeric solution while the core materials could either be dissolved or dispersed in the coacervating solvent. In summary, microencapsulation not only circumvents the color-staining problem but also improved the stability and flowability of curcumin. The solubility of core material in aqueous polymeric solution plays a pivotal role in determining the successful formation of microcapsules.     

Effects of solvents on characteristics of crystalline lactose extracted in ternary and quaternary systems

In a technique referred to as lactose extractive crystallisation, a volatile solvent was added to a solution of lactose dissolved in water. As this second solvent was miscible in water, its presence in the saturated or supersaturated lactose solution would reduce the lactose solubility and hence lactose crystals were formed and grew in the ternary system lactose–ethanol–water. It was found that selecting ethanol as a second solvent could produce needle-shaped crystals having the lowest median size of 8 μm, and β-lactose content up to 60% at 60 °C. On the other hand, using two miscible solvents, one non-volatile and one volatile, such as by adding ethanol to the ternary system, lactose–water–glycerol, crystals having large needle-like or trapezoidal shape and β-lactose content up to 90% could be made at 70 °C. The triangle diagram comparing the solubility of lactose in the glycerol and ethanol aqueous solutions at equilibrium and at different temperatures is presented for the first time. Based on this diagram, it is suggested that the weight ratios of two solvents used and reaction temperatures could be manipulated to produce lactose crystals with different characteristic properties.     

Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.     

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。     

广藿香油微胶囊的制备与性能

以广藿香油为芯材,壳聚糖(CTS)、壳聚糖季铵盐(HACC)、阿拉伯胶(GA)为壁材,采用复凝聚法制备了广藿香油微胶囊。采用扫描电子显微镜(SEM)、激光粒度仪、傅立叶红外光谱(FT-IR)对微胶囊进行表征,并对其热稳定性、缓释性、抗菌性进行了研究。结果表明,微胶囊球形规则、分散性好,湿囊的平均粒径为10.8μm,微胶囊化提高了广藿香油的热稳定性。在相对湿度24%,37℃密封环境中储藏20 d,微胶囊对金黄色葡萄球菌、大肠杆菌的最小杀菌浓度分别为1.25 mg/mL和2.5 mg/mL。     

Morphologies and release behavior of polyurea microcapsules from different polyisocyanates

Polyurea microcapsules were prepared by emulsion polymerization after adding an aqueous solution with poly(vinyl alcohol) as protective colloid into an organic solution with migrin oil as core material, 1,4-diamino anthraquinone (DAA) as penetrator, and different molar ratios of isophorone diisocyanates (IPDI) and toluene diisocyanates (TDI) as wall materials. The effects of diisocyanate types on the morphologies and release behavior of the resultant microcapsules were investigated. The transmittance (%) of the completely dissolved microcapsule in dimethyl acetamide (DMAc) by UV/visible spectrophotometer decreased with the content of aliphatic IPDI in the wall by increasing the wall thickness due to its inferior reactivity compared to aromatic TDI. Also in SEM images, these polyurea microcapsules from higher TDI content had rougher surfaces. In conclusion, the release profiles of the microcapsules in extraction solution showed that release rate of DAA depended on the roughness of the microcapsules.     

Processing conditions for the production of polystyrene microcapsules containing demineralized water

Microencapsulation has been important for engineering, biology, medicine, and several other fields of science. Microencapsulation is an effective way to protect the encapsulated material (e.g. an aqueous solution or pharmaceutical drug) and control its release to the external environment. Microcapsules are also used for producing anticorrosion systems and, in this case, studies about polymeric microcapsules containing acid solutions are relevant. In this paper, polystyrene microcapsules containing demineralized water were produced. The influence of the core-to-shell ratio, evaporation temperature, and the presence of sodium chloride and a surfactant on the yield of the microencapsulation process was evaluated. Microcapsules were characterized by scanning electron microscopy (SEM), and thermogravimetry that revealed the morphology and thermal behavior of microcapsules in response to changing core-to-shell ratios. SEM images showed mononuclear microcapsules with smooth surfaces. The results indicated that a core-to-shell ratio of 2:1 showed the best encapsulation performance under the conditions of this study. An increase in yield of about 38% was achieved by reducing the evaporation temperature. In addition, the yields obtained in this research are considerably higher than those found in literature.     

一种细菌纤维素/姜黄素复合材料的制备及表征

采用原位吸附法，将细菌纤维素（Bacterial Cellulose，BC）浸渍在不同浓度的姜黄素乙醇溶液中，经超声震荡，使BC对姜黄素吸附饱和，获得不同浓度下的BC/姜黄素复合材料。采用SEM、FTIR、XRD及水接触角测量仪等对BC/姜黄素复合材料性能进行测试表征。测试结果表明，原位吸附法成功地将姜黄素固定在BC材料中，随着姜黄素乙醇溶液浓度的提高，BC中吸附姜黄素的量增加，同时将试样置于潮湿环境下，吸附姜黄素的试样具有抗霉变特性，是一种具有应用前景的包装材料或组织工程材料。     

Conjugation of curcumin with PVP capped gold nanoparticles for improving bioavailability

Curcumin, a natural polyphenolic compound, has astounding therapeutic applications but lacks in bioavailability mainly due to its poor solubility in water. Polyvinyl pyrrolidone (PVP) which is a proven drug carrier has been used to facilitate the conjugation of curcumin with gold nanoparticles and to improve the solubility of curcumin in water. In this conjugate diaryl heptanoid chromophore group of curcumin which is a much needed group in biomedical applications remains intact as observed from FTIR and UV–vis spectroscopy analysis. The work shows good promise for such conjugates as therapeutic-cum-imaging materials in biomedical field.     

聚酰亚胺膜溶剂体系的筛选及其作用

采用一种新型的可溶性聚酰亚胺ODPA-BAPP为膜材料,分别用溶度参数法和黏度法对溶剂进行了筛选,然后选定N-甲基吡咯烷酮(NMP)作为溶剂,分别采用挥发性强的四氢呋喃、丙酮、乙醚作为第二溶剂(共溶剂),讨论了它们对成膜过程中的凝胶速率及形成的膜表面形貌的影响.实验结果表明:(1)NMP对ODPA-BAPP的溶解性最好;(2)第二溶剂的挥发性能越好,浇铸膜时的凝胶速率就越慢,就越利于形成表面致密结构的膜.     

Development and characterization of clay facial mask containing turmeric extract solid dispersion

Objective: To develop clay facial mask containing turmeric extract solid dispersion (TESD) for enhancing curcumin water solubility and permeability and to determine suitable clay based facial mask.

Methods: The TESD were prepared by solvent and melting solvent method with various TE to polyvinylpyrrolidone (PVP) K30 mass ratios. The physicochemical properties, water solubility, and permeability were examined. The effects of clay types on physical stability of TESD, water adsorption, and curcumin adsorption capacity were evaluated.

Results: The TESD prepared by solvent method with a TE to PVP K30 mass ratio of 1:2 showed physically stable, dry powders, when mixed with clay. When TESD was dissolved in water, the obtained TESD micelles showed spherical shape with mean size of ～100?nm resulting in a substantial enhancement of curcumin water solubility,?～5?mg/ml. Bentonite (Bent) and mica (M) showed the highest water adsorption capacity. The TESD’s color was altered when mixed with Bent, titanium dioxide (TiO₂) and zinc oxide (ZnO) indicating curcumin instability. Talcum (Talc) showed the greatest curcumin adsorption followed by M and kaolin (K), respectively. Consequently, in vitro permeation studies of the TESD mixed with Talc showed lowest curcumin permeation, while TESD mixed with M or K showed similar permeation profile as free TESD solutions. The developed TESD-based clay facial mask showed lower curcumin permeation as compared to those formulations with Tween 80.

Conclusion: The water solubility and permeability of curcumin in clay based facial mask could be improved using solid dispersion technique and suitable clay base composed of K, M, and Talc.     

P84共聚聚酰亚胺湿法纺丝溶剂的选择

P84共聚聚酰亚胺能溶于常见的非质子溶剂进行湿法纺丝。良溶剂可以制得性能稳定的纺丝浆液,这对得到结构相对密实的聚酰亚胺纤维很重要。本文从聚合物和溶剂溶度参数的计算,P84共聚聚酰亚胺在不同溶剂中的特性黏度测试以及P84共聚聚酰亚胺/溶剂/水三元体系的相图三方面出发,比较分析了较适合P84共聚聚酰亚胺湿法纺丝的溶剂。结果表明,P84的溶度参数为10.35,与N-甲基吡咯烷酮(NMP)和N,N′-二甲基乙酰胺(DMAc)的溶度参数(分别为11.23和11.14)较接近;P84-NMP,P84-DMAc和P84-DMF的特性黏度分别是0.807,0.657和0.615;结合相图得到NMP、DMAc以及N,N′-二甲基甲酰胺(DMF)比较适合P84湿法纺丝,其中NMP最佳。     

Curcumin associated magnetite nanoparticles inhibit in vitro melanoma cell growth

Curcumin is a natural product possessing therapeutic properties but the low water solubility of this compound limits its use. We have successfully incorporated curcumin into a bilayer of dodecanoic acid attached to magnetite nanoparticles in an effort to maximize solubility and delivery efficiency. Curcumin/magnetite nanoparticles were characterized using diffused reflectance infra-red fourier transform spectroscopy (DRIFTS) and X-ray powder diffraction (XRD). Moreover curcumin associated magnetite nanoparticles inhibited in vitro melanoma cell growth. An inhibitory concentration (IC50) of 66.0 +/- 3.0 microM (48 +/- 2.2 microg-iron/mL) was observed for the curcumin/magnetite nanoparticles. Fluorescent microscopy revealed that curcumin associated magnetite nanoparticles were internalized by the melanoma cells and remained in the cytoplasm. The curcumin/magnetic nanoparticles synthesized in this study possess magnetic and water solubility properties making this a novel curcumin formulation with therapeutic potential.     

Release of Ibuprofen from Polyethylene glycol solid dispersions:-Equilibrium solubility approach

This work is an attempt to enhance the release of Ibuprofen by improving its aqueous solubility. This was done by dispersing the drug in a water soluble carrier such as polyethylene glycol (PEG). The solubility was found to depend on various factors such as method of preparation, carrier weight fraction and molecular weight and the pH of the medium. It was found that dispersions prepared by the fusion method gave higher solubilities than those prepared by the solvent technique. The solubility was found to vary with carrier molecular weight and its weight fraction. Decreasing the PEG molecular weight resulted in increased solubility. A polymer to drug ratio of 1:1 was found to give the highest solubility. The solubility decreased as the polymer weight fraciton was increased beyond this value. The solubility of the solid dispersion was found to be pH dependent. A greater solubility was obtained at higher pHs than at lower ones. This was attributed to the weakly acidic nature of Ibuprofen. Calculation of the heat of solution of the various systems studied showed that the non dispersed drug had a higher heat of solution than the dispersed systems. This was thought to be the cause of the higher solubility of the dispersions as compared to the original drug.     

Synthesis and characterization of silica microcapsules using a sustainable solvent system template

We report direct encapsulation of a sustainable solvent system in silica microcapsules via a sol-gel reaction of silica precursor for potential application of thermoplastic self healing polymeric system. The silica microcapsules were realized by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) using aqueous glycerol microemulsion as template. The pre-hydrolysis of TEOS was found to be useful to obtain isolated free flowing silica microcapsules. Furthermore, the effects of different parameters viz. temperature, rotor speed, the solvent/TEOS ratio on the synthesis of silica microcapsules are studied. A novel micro compression technique to study mechanical properties of the silica microcapsules is reported. The silica microcapsules reported were found to have better mechanical properties compared to incumbent Urea-Formaldehyde (UF) based organic microcapsules.     

肉桂精油微囊化及其在果蔬保鲜中的应用

目的以壳聚糖、海藻酸钠为壁材,以肉桂精油为芯材,采用复凝聚法制备壳聚糖微胶囊,并将其应用于水果保鲜中。方法通过光学显微镜、扫描电子显微镜、傅里叶转化红外光谱等,确定微胶囊的最佳工艺参数、芯壁比及添加质量分数,并以芒果为实验对象,研究添加不同微胶囊质量分数的壳聚糖溶液对芒果保鲜效果的影响。结果当壳聚糖/海藻酸钠质量比为1∶2,氯化钙质量分数为1%,p H值为5,戊二醛质量分数为60%,交联时间为60 min,芯壁比为4∶1时,制备形成的壳聚糖微胶囊成球效果较好;微胶囊在壳聚糖溶液中的添加质量分数为4%时,以其涂膜的芒果保鲜效果最佳。结论肉桂精油经囊化后有效减少了气味、延缓了挥发,在果蔬保鲜中有较重要的现实研究意义。     

S/O型可逆热变色微胶囊的制备与性能

为改善无机热变色材料的可逆性能,采用油相相分离法,以无机变色颜料镍的化合物为芯材,乙基纤维素(EC)为壳材料,环己烷(HC)为溶剂,制备了S/O型可逆热变色微胶囊,并研究了微胶囊的结构、热稳定性和变色性能等。结果表明,S/O型可逆热变色微胶囊提高了芯材的热变色性能,具有良好的包裹和较强的保护作用。     

Release of Ibuprofen from Polyethylene glycol solid dispersions:-Equilibrium solubility approach

Abstract

This work is an attempt to enhance the release of Ibuprofen by improving its aqueous solubility. This was done by dispersing the drug in a water soluble carrier such as polyethylene glycol (PEG). The solubility was found to depend on various factors such as method of preparation, carrier weight fraction and molecular weight and the pH of the medium. It was found that dispersions prepared by the fusion method gave higher solubilities than those prepared by the solvent technique. The solubility was found to vary with carrier molecular weight and its weight fraction. Decreasing the PEG molecular weight resulted in increased solubility. A polymer to drug ratio of 1:1 was found to give the highest solubility. The solubility decreased as the polymer weight fraciton was increased beyond this value. The solubility of the solid dispersion was found to be pH dependent. A greater solubility was obtained at higher pHs than at lower ones. This was attributed to the weakly acidic nature of Ibuprofen. Calculation of the heat of solution of the various systems studied showed that the non dispersed drug had a higher heat of solution than the dispersed systems. This was thought to be the cause of the higher solubility of the dispersions as compared to the original drug.     

自修复微胶囊复合材料的制备及力学性能研究

为了提高树脂基复合材料的使用寿命,以脲醛树脂为壁材,双环戊二烯为囊芯,通过原位聚合法制备了内含修复液的微胶囊,探讨了反应过程中脲醛量比及乳化剂用量等对微胶囊表面形貌和结构的影响.通过优化工艺条件制备出表面致密的微胶囊,并将微胶囊埋植在环氧树脂基体中制备复合材料.采用扫描电镜对胶囊进行形貌表征,运用快速傅里叶变换红外光谱...     

Eudragit Microcapsules of Nifedipine and Its Dispersions in HPMC-MCC: Physicochemical Characterization and Drug Release Studies

Nifedipine and its solid dispersions in hydroxypropyl methyl cellulose-microcrystalline cellulose (HPMC-MCC) were microencapsulated with Eudragit RL PM by an emulsion solvent evaporation method. The microcapsules are spherical, discrete, free flowing, and covered with a continuous coating of the polymer. XRD and DTA indicated the presence of nifedipine in solution form in the solid dispersions and their microcapsules. No chemical interaction between nifedipine and excipients in the microcapsules was observed. Nifedipine as such and its microcapsules gave very slow release because of its highly crystalline nature and poor solubility. Solid dispersion in HPMC-MCC gave fast and rapid dissolution of nifedipine. When these solid dispersions were microencapsulated a slow, controlled, and complete release over a period of 12 hr was observed from the resulting microcapsules. Drug release depended on the proportion of HPMC-MCC in the solid dispersion used as a core, coat, core ratio, and size of the microcapsules. Release was independent of pH and ionic strength. Drug release was governed by diffusion rate and followed first-order kinetics.