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1.
A strategy to incorporate and release anti-cancer drugs of daunorubicin (DNR) and doxorubicin (DOX) in preformed microcapsules is introduced, which is based on charge interaction mechanism. Oppositely charged poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were assembled onto PSS doped-CaCO3 colloidal particles in a layer-by-layer manner to yield core-shell particles. After removal of the carbonate cores, hollow microcapsules with entrapped PSS were fabricated, which showed spontaneous loading ability of positively charged DNR and DOX. The drug loading was confirmed quantitatively by observations under confocal laser scanning microscopy, transmission electron microscopy and scanning force microscopy. Quantification of the drug loading was performed under different conditions, revealing that a larger amount of drugs could be incorporated at higher drug feeding concentrations and higher salt concentrations. However, putting additional polyelectrolyte layers on the microcapsules after core removal resulted in weaker drug loading efficiency. The drug release behaviors from the microcapsules with different layer numbers were studied too, revealing a diffusion controlled release mechanism at the initial stage (4 h). 相似文献
2.
Microencapsulation of cinnamon leaf (Cinnamomum zeylanicum) and garlic (Allium sativum) oils in β-cyclodextrin 总被引:1,自引:0,他引:1
J. Fernando Ayala-Zavala Herlinda Soto-Valdez Alberto González-León Emilio Álvarez-Parrilla Olga Martín-Belloso Gustavo A. González-Aguilar 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):359-368
Cinnamon leaf (CLO) and garlic oils (GO) are good antimicrobials, however, their volatility complicates their application
as food preservatives. Hence, microencapsulation of CLO and GO with β-cyclodextrin (β-CD) was studied at 4:96, 8:92, 12:88,
and 16:84 (oil:β-CD) percent weight ratios. Microcapsule characterization included gas chromatography analysis, moisture sorption–desorption
isotherms, infrared spectroscopy (IR), and antifungal activity against Alternaria alternata. Major oil constituents were eugenol for CLO and allyl disulfide for GO. The 16:84 ratio (CLO:β-CD) showed the highest eugenol
content; the allyl disulfide content was higher, but not significantly different (P > 0.05) for the 12:88 and 16:84 ratios. Microcapsules showed lower moisture sorption than β-CD, although during water desorption
there were no difference between them. Hydrogen bonds were detected between oil constituents and β-CD by IR spectroscopy.
CLO:β-CD and GO:β-CD microcapsules displayed good antifungal activity against Alternaria alternata. Therefore, CLO and GO microcapsules can have important applications in the food industry as stable natural antimicrobial
compound systems. 相似文献
3.
采用界面聚合法,以薄荷素油为芯材,以异佛尔酮二异氰酸酯为壁材单体,在催化剂四甲基乙二胺作用下和水反应形成聚脲外壳,制备出了薄荷素油微胶囊.通过扫描电镜、激光粒度分析仪、傅里叶红外光谱仪及热重分析仪分别对香精微胶囊的表面形貌、粒径分布、单体反应情况和热稳定性进行了分析表征.通过紫外可见分光光度计对香精微胶囊包覆率进行了测定.并分析了均质化速率和微胶囊平均粒径的关系以及不同乳化剂种类和芯壁比条件下微胶囊的形貌特征.结果表明,微胶囊平均粒径随均质化速率的增大而减小,下降到1μm左右时趋于平稳,当乳化剂采用聚乙烯醇且芯壁比为4∶1时,微胶囊形貌最佳,为规整球形.最终测得微胶囊芯材包覆率为84.09 wt%,粉末状微胶囊样品含油率为72.64 wt%,并且微胶囊芯材具有良好的热稳定性. 相似文献
4.
In this study, microcapsules were prepared by spray drying and embedding hemp seed oil (HSO) with soy protein isolate (SPI) and maltodextrin (MD) as wall materials. The effect of ultrasonic power on the microstructure and characteristics of the composite emulsion and microcapsules was studied. Studies have shown that ultrasonic power has a significant impact on the stability of composite emulsions. The particle size of the composite emulsion after 450 W ultrasonic treatment was significantly lower than the particle size of the emulsion without the ultrasonic treatment. Through fluorescence microscopy observation, HSO was found to be successfully embedded in the wall materials to form an oil/water (O/W) composite emulsion. The spray-dried microcapsules showed a smooth spherical structure through scanning electron microscopy (SEM), and the particle size was 10.7 μm at 450 W. Fourier transform infrared (FTIR) spectroscopy analysis found that ultrasonic treatment would increase the degree of covalent bonding of the SPI-MD complex to a certain extent, thereby improving the stability and embedding effect of the microcapsules. Finally, oxidation kinetics models of HSO and HSO microcapsules were constructed and verified. The zero-order model of HSO microcapsules was found to have a higher degree of fit; after verification, the model can better reflect the quality changes of HSO microcapsules during storage. 相似文献
5.
Microcapsules containing n-octadecane were successfully fabricated by an in-situ polymerization process with melamine-formaldehyde (MF) prepolymer and
a hydrolyzed copolymer of styrene and maleic anhydride (SMA) as shell materials. To achieve a long service time of microcapsules
containing phase change materials (microPCMs), the compactness of shells was improved by adding the MF prepolymer twice. The
mechanism of this method was a two-step coacervation (TSC) under the help of hydrolyzed SMA compared to a one-step coacervation
(OSC). To understand the influence of both coacervations, properties of shells were investigated in terms of morphologies,
density, thickness, and stability by means of scanning electron microscopy (SEM), transmission electron microscopy, and thermal
gravimetric analysis (TGA). The data of shells thickness were achieved from the cross-section SEM images. It shows that the
average thickness of shells from two kinds of process are 0.1 μm. The density and stability in water of shells fabricated
by TSC are both higher than that of shells by OSC. TGA curves show the expected microPCMs of TSC losing weight from 200 to
400 °C. The release curves, relationship between time and logarithmic residual weight of core, show there are two decrease-linear
steps after curve regression. It can be concluded from all these results that the TSC method may be a promising method leading
to a compact shell structure for various application. 相似文献
6.
A series of microcapsules filled with epoxy resins with poly(urea-formaldehyde) (PUF) shell were synthesized by in situ polymerization, and they were heat-treated for 2 h at 100 °C, 120 °C, 140 °C, 160 °C, 180 °C and 200 °C. The effects of surface morphology, wall shell thickness and diameter on the thermal stability of microcapsules were investigated. The chemical structure and surface morphology of microcapsules were investigated using Fourier-transform infrared spectroscope (FTIR) and scanning electron microscope (SEM), respectively. The thermal properties of microcapsules were investigated by thermogravimetric analysis (TGA and DTA) and by differential scanning calorimetry (DSC). The thermal damage mechanisms of microcapsules at lower temperature (<251 °C) are the diffusion of the core material out of the wall shell or the breakage of the wall shell owing to the mismatch of the thermal expansion of core and shell materials of microcapsules. The thermal damage mechanisms of microcapsules at higher temperature (>251 °C) are the decomposition of shell material and core materials. Increasing the wall shell thickness and surface compactness can enhance significantly the weight loss temperatures (Td) of microcapsules. The microcapsules with mean wall shell thickness of 30 ± 5 μm and smoother surface exhibit higher thermal stability and can maintain quite intact up to approximately 180 °C. 相似文献
7.
C. Cristallini G. Enriquez De Grassi L. Guardines R. Gaussmann 《Applied biochemistry and biotechnology》1984,10(1-3):267-272
A procedure to obtain a controlled-release microencapsulated anti-inflammatory drug based on a solvent evaporation method
is described. The present method makes use of ethylcellulose as the polymer and methylene chloride as solvent. The evaporation
of solvent is controlled by means of an air stream. Variations in the preparative procedure and their effects on capsule dimensions
and permeabilities were studied. The release behavior of the drug is determined, and two different diffusion constants are
also determined: 7.0×10−10 cm2/s and 1.2×10−10 cm2/s, corresponding to low and high release time. Based on these results it is proposed that these microcapsules have a nonhomogeneous
polymeric wall, and are more porous in the outer surface. This model might be applicable to the microcapsules obtained by
means of the solvent evaporation method. 相似文献
8.
固体芯材微胶囊制备技术研究进展 总被引:1,自引:0,他引:1
文章主要介绍了微胶囊研究背景、用途及制备方法。从固体芯材料水溶性的角度,可把芯材分为亲水性和疏水性两种类型。对于水溶性芯材微胶囊的制备方法,介绍了原位聚合法、油相相分离法、喷雾干燥法和喷雾冷凝法的技术进展;对于疏水性芯材,介绍了界面聚合法、原位聚合法、水相相分离法等方法包覆微胶囊的技术进展。此外,本文还对不同类型的固体芯材所适应的制备方法及壳材料进行了探讨,从试验条件、芯材料的特性及目标产品性能等角度来选取适当的微胶囊壳材及制备方法,以期探索出更经济、实用、高效的固体芯材微胶囊化制备方法。 相似文献
9.
10.
Rong Lu Hongjing Dou Yuanyuan Qiu Dong Zhang Kang Sun Yuqi Zhang Kun Sun 《Colloid and polymer science》2009,287(6):683-693
Polymeric microcapsules are of great potential in ultrasonic imaging due to their characteristic hollow structure. Water-in-oil-in-water
(W1/O/W2) double emulsion-solvent evaporation technique is a versatile strategy applicable to most hydrophobic polymers for fabricating
microcapsules; however, the adjustment of the size and inner structure of resultant microcapsules have not been systematically
studied until now. Here, we evaluate in detail the parameters in double emulsification and find that the W1/O volume ratio is a pivotal parameter which controls the hollow structure of microcapsules. In addition, an appropriate concentration
of emulsifier in W2 is essential to guarantee the hollow structure as well. For quantitatively characterizing the hollow structure of microcapsules,
we propose the concept of Hollow Ratio (HR) and Hollow Degree (HD) to evaluate the percent of hollow microcapsules in products
and the hollow characteristic of the microcapsules. Our study demonstrates that the HR of microcapsules can vary between 25%
and 98% by only adjusting the W1/O volume ratio. The size of microcapsule has a close relationship to its HD. Moreover, the microcapsules with both single
cavity and multicavities have been fabricated by altering the energy of the second emulsification. Further, acoustic studies
reveal that the microcapsules with different HD display obviously different sound attenuation spectrum and resonance frequency,
which demonstrates that the adjustment of hollow structure should be an effective approach to control the acoustical properties
of microcapsules for ultrasonic imaging. 相似文献