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The objective of this study was to achieve the colon-specific delivery of an anti-ulcerative colitis drug using hydroxypropyl methyl cellulose (HPMC) hydrogels. HPMC hydrogels containing poly ethylene glycol (PEG) as cross-links have been prepared by reacting HPMC sodium salt with polyethylene glycol dichloride.
The effect of cross-linking agent on swelling behavior of HPMC-PEG hydrogels, were investigated. Swelling parameters such as equilibrium degree of swelling, swelling ratio and network parameter such as molecular mass between cross-links (Mc) were determined. The cross-linking concentrations were 0.5%, 1%, 1.5%, and 2% (based on weight of HPMC). The equilibrium swelling ratio (Q) of cross-linked HPMC hydrogels increases from 13.2 to 27.1 as the cross-linker percentage increases from 0.5% to 2%. 5-Aminosalicylic acid (5-ASA) was used as a model of an anti-inflammatory drug. Cross-linked HPMC hydrogels were found to be a promising drug delivery system for the drugs to be delivered to the colon. 相似文献
The effect of cross-linking agent on swelling behavior of HPMC-PEG hydrogels, were investigated. Swelling parameters such as equilibrium degree of swelling, swelling ratio and network parameter such as molecular mass between cross-links (Mc) were determined. The cross-linking concentrations were 0.5%, 1%, 1.5%, and 2% (based on weight of HPMC). The equilibrium swelling ratio (Q) of cross-linked HPMC hydrogels increases from 13.2 to 27.1 as the cross-linker percentage increases from 0.5% to 2%. 5-Aminosalicylic acid (5-ASA) was used as a model of an anti-inflammatory drug. Cross-linked HPMC hydrogels were found to be a promising drug delivery system for the drugs to be delivered to the colon. 相似文献
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《Drug development and industrial pharmacy》2013,39(6):628-637
Aim: To investigate the physicochemical stability, pharmacokinetics (PK), and biodistribution of paclitaxel (PTX) from paclitaxel solid dispersion (PSD) prepared by supercritical antisolvent (SAS) process.Methods: Physicochemical stability was performed in accelerated (40°C 70?±?5% RH) and stress (60°C) storage conditions for a period of 6 months and 4 weeks, respectively. PK and biodistribution studies were performed in rats following i.v. administration of PTX equivalent to 6 and 12?mg/kg formulations.Results: Physical stability of PSD showed excellent stability with no recrystallization of the amorphous form. Chemical stability of PSD in terms of % PTX remaining was 98.2?±?0.6% at 6 months and 97.9?±?0.3% at 4 weeks of accelerated and stress conditions, respectively. The PK study showed a nonlinear increase in AUC with increasing dose, that is, 100% increase in dose (from 6 to 12?mg/kg) resulted in 405.90% increase in AUC. Unlike PK study, the organ distribution study of PTX from PSD showed linear relationship with dose escalation. The order of organ distribution of PTX from highest to lowest for both PSD and Taxol® was liver>kidney>lung>brain.Conclusions: This study demonstrated excellent physicochemical stability with insight information on the PK and biodistribution of PTX from PSD prepared by SAS process. 相似文献
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E. M. Elsayed A. E. Shalan M. M. Rashad 《Journal of Materials Science: Materials in Electronics》2014,25(8):3412-3419
Zinc oxide thin films have been successfully prepared by co-precipitation and electrodeposition methods onto Fluorinated tin oxide substrate using zinc nitrate aqueous solutions at various bath temperatures (25–75 °C). The deposition of electrodeposition method was conducted using both using linear sweep voltammetry and Chronoamperometric techniques. The effects of solution composition, agitation and bath temperature on the electrochemical measurements and ZnO film characteristics were fully analyzed. The findings reveal that temperature and nitrate ion concentration have a strong promoting effect on ZnO film formation. Moreover, the obtained powders were investigated by X-ray diffraction, Field emission scanning electron microscopy and UV–Vis Spectroscopy. Structural characterization by X-ray diffraction indicates the formation of ZnO phase and the deposited film exhibits the Zincite structure with crystallite size around 51 nm. The photovoltaic performance of dye-sensitized solar cells based on both ZnO prepared by co-precipitation and electrodeposition methods was investigated. A power conversion efficiency (η) of 3.5 % was achieved for the DSSC with co-precipitation ZnO, which is higher than that of the cell with electrodeposition ZnO (2.5 %). Explanations are substantiated by incident photon to electron conversion efficiency curves. 相似文献
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《Journal of Experimental Nanoscience》2013,8(3):183-192
D-alpha-tocopheryl poly (ethylene glycol) 1000 succinate (TPGS) is a widely used form of vitamin E that has been used as a solubilizer, an emulsifier and as a vehicle for drug delivery formulations. In this study, poly lactide-co-glycolide (PLGA) nanoparticles were prepared by spontaneous emulsification solvent diffusion (SESD) method. TPGS as an emulsifier and further as a matrix material blended with PLGA was used to enhance the encapsulation efficiency and improve the drug release profile of nanoparticles. Rifampicin and estradiol valerate were used as model drugs with different water solubility. The effect of formulation parameters such as drug/polymer ratio, oil phase combination, volume and surfactant content was evaluated. The surface morphology and size of the nanoparticles were studied by scanning electron microscopy (SEM) and laser light scattering. Drug encapsulation efficiency and in vitro drug release profiles of nanoparticles were determined using high performance liquid chromatography (HPLC). The nanoparticles prepared in this study were spherical with size range of 150–250?nm. It was shown that TPGS was a good emulsifier for producing nanoparticles of hydrophobic drugs and improving the encapsulation efficiency and drug loading and drug release profile of nanoparticles. However, the drug loading efficiency of rifampicin, a slightly water-soluble molecule, was significantly lower than that of estradiol valerate, a water insoluble molecule. 相似文献
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用水热、溶剂热方法制备纳米CdS粒子及其光催化性能 总被引:14,自引:0,他引:14
以硫化钠和硫代乙酰胺为硫源,用水热和溶剂热方法制备了不同粒径的纳米硫化镉半导体光催化剂.借助X射线衍射(XRD),UV-Vis漫反射对CdS催化剂进行了表征.以甲酸水溶液的光催化制氢反应为探针,评价了不同合成方法对催化剂活性的影响;用电化学方法测定了CdS光腐蚀程度.结果表明,反应物、溶剂与温度等都可影响CdS晶型与结晶度,导致其光催化活性差异;CdS光腐蚀性与其晶型有关,并随结晶度的提高显著降低,这说明通过控制合适的条件可制备高活性低腐蚀的CdS. 相似文献
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Preparation of polypyrrole nanoparticles in reverse micelle and its application to glucose biosensor
Ren X Zhao Q Liu J Liang X Zhang Q Zhang P Luo Z Gul Y 《Journal of nanoscience and nanotechnology》2008,8(5):2643-2646
Polypyrrole nanoparticles were successfully synthesized in cetyltrimethyl ammonium bromide (CTAB)/hexanol/water reverse micelle. The morphology and particle size of the obtained nanoparticles were characterized with transmission electron microscope (TEM) and scanning electron microscopy (SEM). Glucose biosensors were formed with glucose oxidase (GOx) immobilized in conducting composite material consisting of polypyrrole nanoparticles and ethyl cellulose. The effects of reaction conditions such as molar ratio of polypyrrole nanoparticles to ethyl cellulose, working voltage, glucose concentration, temperature and solution pH on the electrochemical response of the GOx electrode were studied. Experimental results showed that the linear range of GOx electrode was 1.0 x 10(-6)-6 x 10(-3) mol/L and the detection limit was 1.0 x 10(-7) mol/L. The electrode exhibited fine repeatability and selectability, and its lifetime was greater than one month. AFM showed that the surface of conducting composite material-glucose oxidase electrode's presents uniform granular after washing paraffin wax with cyclohexane, which was favorable for enzyme-catalyzed reaction. 相似文献
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Huang H Qu C Liu X Huang S Xu Z Liao B Zeng Y Chu PK 《ACS applied materials & interfaces》2011,3(2):183-190
We report a novel shell technique to prepare controllable core-shell nanoparticles. In this technique, the shell is formed when the core reacts with metal ions and Na(2)S(2)O(3) and the size of the core and thickness of the shell can be controlled. Transmission electron microscopy and X-ray diffraction reveal that the shell consists of insoluble complex salts comprising Au(2)S, AuAgS, and Ag(3)AuS(2). The resulting core-shell nanoparticles obtained at different reaction stages demonstrate that the formation of Au(2)S, AuAgS, and Ag(3)AuS(2) shell proceeds from the outside. The morphological evolution of the particles changes significantly with reaction time demonstrating that formation of the shell results from diffusion in the solid shell. The core-shell nanoparticles produced by this technique can be used as nanosensors to detect Ag(+) in aqueous media with high selectivity and sensitivity. The excellent selectivity for Ag(+) is demonstrated by comparing the response to other metal ions. In addition, our evaluation indicates that gold nanorods offer higher sensitivity than gold nanospheres. 相似文献
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Yu. F. Kargin S. N. Ivicheva E. Yu. Buslaeva T. B. Kuvshinova V. D. Volodin G. Yu. Yurkov 《Inorganic Materials》2006,42(5):487-490
Bismuth nanoparticles have been produced in pores of opal matrices by reducing bismuth salts and oxide compounds with supercritical isopropanol. According to transmission electron microscopy data, the diameter of the SiO2 spheres in the opal matrices is about 260 nm, and that of the bismuth nanoparticles does not exceed 80 nm. 相似文献
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以天然的纳米纤维素(NFC)为分散剂,利用其亲水亲油的特性,将其用于剥离和分散片层黏土,成功攻克单片层黏土易发生絮聚的缺陷,高获得率制备出NFC分散的具有优异稳定性的单片层黏土分散液,并采用AFM和TEM对NFC和单片层黏土的形貌进行表征。最后,将单片层黏土分散体与NFC结合成功制备出一种高透明柔性薄膜。当单片层黏土含量为50wt%时,NFC/单片层黏土复合薄膜在600~800 nm波长下的透光率高达90%,且呈现较低的雾度。此外,该薄膜还具有优异的紫外阻隔能力,在紫外区能完全阻隔短波紫外线(UVC,波长为100~290 nm),阻隔大部分中波紫外线(UVB,波长为290~320 nm)。NFC分散的具有优异稳定性的单片层黏土分散液的成功制备,将有助于拓展纳米黏土的应用领域及提高单片层黏土基复合材料的性能。 相似文献
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Chie Inui Hiroaki Kura Tetsuya Sato Yosuke Tsuge Seimei Shiratori Hisanori Ohkita Akihiro Tagaya Yasuhiro Koike 《Journal of Materials Science》2007,42(19):8144-8149
Surface-modified ZnTe nanoparticles were mixed in a zero-birefringence polymer matrix. Transmission electron microscopy images
revealed that aggregates of ZnTe nanoparticles with a diameter of ∼20 nm were uniformly dispersed in the polymer. The transmittance
of ZnTe nanocomposites rapidly decreased at wavelengths shorter than the critical wavelength corresponding to the band gap
of ZnTe nanoparticles, an effect which became significant as the volume fraction of particles increased. In this way, the
optical characteristic of ZnTe nanoparticles was added to the polymer. The intrinsic zero-birefringence was confirmed in the
heat-drawn ZnTe nanocomposites. As the ZnTe nanocomposites were left in air, a lowering of transmittance was observed. This
was due to the oxidation of Zn and the resultant deposition of Te in the ZnTe nanocomposite, as the light absorption of Te
is significant. The formation of oxygen non-permeable SiO2 films onto the ZnTe nanocomposite by the sol-gel method was useful in preventing oxidation so that the decrement of transmittance
decreased from 47.2% to 14.9% at 530 nm near the ZnTe band gap. 相似文献
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Copper nanoparticles were successfully synthesized by the borohydride reduction of copper nitrate salt in water/CH3CN mixed solvent under inert argon-purged conditions. Cu nanoparticles were synthesized in large-scale production for the first time by introducing CH3CN into water and preventing oxidation during the preparation of nanoparticles. Nanoparticles were characterized by using UV-visible absorption spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. High resolution TEM pictures showed the formation of homogeneous cubic-structured copper nanoparticles with sizes less than 100 nm. This new kind of synthesis method shows the excellent stability compared with that of citrate-protected copper nanoparticles, which may provide an efficient way to improve the fine tuning of the structure and size of copper nanoparticles. 相似文献
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Information relating to tannin concentration in grapes and wine is not currently available simply and rapidly enough to inform decision-making by grape growers, winemakers, and wine researchers. Spectroscopy and chemometrics have been implemented for the analysis of critical grape and wine parameters and offer a possible solution for rapid tannin analysis. We report here the development and validation of an ultraviolet (UV) spectral calibration for the prediction of tannin concentration in red wines. Such spectral calibrations reduce the time and resource requirements involved in measuring tannins. A diverse calibration set (n = 204) was prepared with samples of Australian wines of five varieties (Cabernet Sauvignon, Shiraz, Merlot, Pinot Noir, and Durif), from regions spanning the wine grape growing areas of Australia, with varying climate and soils, and with vintages ranging from 1991 to 2007. The relationship between tannin measured by the methyl cellulose precipitation (MCP) reference method at 280 nm and tannin predicted with a multiple linear regression (MLR) calibration, using ultraviolet (UV) absorbance at 250, 270, 280, 290, and 315 nm, was strong (r(2)val = 0.92; SECV = 0.20 g/L). An independent validation set (n = 85) was predicted using the MLR algorithm developed with the calibration set and gave confidence in the ability to predict new samples, independent of the samples used to prepare the calibration (r(2)val = 0.94; SEP = 0.18 g/L). The MLR algorithm could also predict tannin in fermenting wines (r(2)val = 0.76; SEP = 0.18 g/L), but worked best from the second day of ferment on. This study also explored instrument-to-instrument transfer of a spectral calibration for MCP tannin. After slope and bias adjustments of the calibration, efficient calibration transfer to other laboratories was clearly demonstrated, with all instruments in the study effectively giving identical results on a transfer set. 相似文献
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A green route for the synthesis of palladium (Pd) nanoparticles (Pd NPs) employing Poplar leaf extract as a reducing and capping agent is described. The as‐prepared Pd NPs are spherical with a face centred cubic structure, a particle distribution of 2.2–6.8 nm and an average particle size of 4.2 nm. The application of this catalyst toward homogeneous Suzuki coupling reactions was investigated. The Pd NPs afforded a yield of 98.86% in the Suzuki coupling reaction of 4‐bromotoluene with phenylboronic acid using 0.01 mmol% of the catalyst at 60°C for 30 min under an air atmosphere.Inspec keywords: palladium, nanoparticles, nanofabrication, particle size, catalysts, organic compounds, nanobiotechnologyOther keywords: biosynthesis, palladium nanoparticles, Poplar leaf extract, green route, reducing agent, capping agent, face centred cubic structure, particle size, catalyst, homogeneous Suzuki coupling reactions, 4‐bromotoluene, phenylboronic acid, size 4.2 nm, temperature 60 C, Pd 相似文献