Sustained release of ethyl cellulose micro-particulate drug delivery systems prepared using electrospraying

Sustained-release ethyl cellulose (EC) micro-particles were prepared by electrospraying. Ketoprofen (KET) was taken as a model drug and various concentrations of EC functioned as a rate-controlling polymer. The morphology of the micro-particles was assessed using SEM. Images showed that as EC content increased, the granules shared similar surface characteristics containing pure EC. Micro-particle structures were analyzed by DSC, XRD, and FTIR. It was noted that the crystalline drug was converted into an amorphous form in all the granulations and that there was chemical interaction between KET and EC observed from FTIR. Dissolution studies revealed that as the amount of EC increased, the drug release rate decreased. This investigation suggests that electrospraying can be exploited as a useful tool for developing novel particulate drug delivery systems.     

Preparation and characterization of ketorolac tromethamine-loaded ethyl cellulose micro-/nanospheres using different techniques

Sustained-release micro-/nanospheres of the ketorolac tromethamine (KTC) were prepared using four different techniques viz., single emulsion solvent evaporation, high pressure homogenization, spray drying, and using a microreactor. Ethyl cellulose (EC) was used as an encapsulating agent for the preparation of sustained-release micro-/nanospheres of KTC. The Plackett–Burman design was employed for design of the experiments. The resulting micro-/nanospheres were characterized for their size, morphology, encapsulation efficiency, and in vitro drug release performance. Interactions between the KTC and EC were quantified by Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffractometry (XRPD). Particle morphology characterization was performed using field emission scanning electron microscopy. The micro-/nanospheres showed encapsulation efficiency of 42.34–89.33% by the solvent evaporation technique, 76.36–91.13% by the high-pressure homogenization technique, 70.74–79.68% by spray drying, and 79.00–89.49% by the microreactor technique. The micro-/nanospheres were found to be spherical and oval with smooth surface. The FTIR analysis confirmed no interaction of KTC with EC polymer. The XRPD analysis revealed good dispersion of the drug within the micro-/nanospheres formulation. Sustained KTC release profile over 12?h was achieved successfully by EC polymer. In conclusion, EC sustained-release micro-/nanospheres containing KTC can be prepared successfully using different techniques.     

Dielectric properties of solution-grown-undoped and acrylic-acid-doped ethyl cellulose

Dielectric capacities and losses were measured, in the temperature (50–170°C) and frequency (01–100 kHz range), for undoped and acrylic acid (AA) doped ethyl cellulose (EC) films (thickness about 20 μm) with progressive increase in the concentration of dopant in the polymer matrix. The variation of capacity with temperature is attributed to thermal expansion in the lower temperature region to the orientation of dipolar molecules in the neighbourhood of glass transition temperature (T _g) and random thermal motion of molecules aboveT _g. The dielectric losses exhibit a broad peak. Doping with AA is found to affect the magnitude and position of the peak. AA is found to have a two-fold action. Firstly, it enhances the chain mobility and secondly, it increases the dielectric loss by forming charge transfer complexes.     

乙基纤维素微胶囊红磷的制备及改性

目前微胶囊红磷大多采用原位聚合法制备,工艺较为复杂,且囊壳原料可能对环境造成危害.为解决这一问题,以可降解材料乙基纤维素(EC)为囊壳,采用相分离法在常温、中性条件下制备微胶囊红磷(MRP);为进一步增强MRP使用性能,添加正硅酸乙酯(TEOS)作为改性材料,在碱性条件下制备SiO_2凝胶/EC复合囊壳微胶囊红磷(SiMRP).对所得样品进行FTIR、形态及XPS分析,观察样品形态并计算包覆率;对样品进行热稳定性分析、吸湿率测定及安定性测试.实验结果表明:采用相分离法可对红磷实现有效包覆,囊壳包覆率为88.2%;EC囊壳提高了红磷的热稳定性,着火点温度较RP提升50℃; MRP 10日后吸湿率降至6.8%,摩擦感度降至34%;添加1 mL TEOS改性后的SiMPR样品包覆率达94.1%,热稳定性较MRP进一步增强,着火点温度较MRP提升90℃;SiMRP 10日后吸湿率降至4.5%,摩擦感度降至20%.     

Analysis of cellulose networks by the finite element method

Paper can be regarded as a network of cellulosic fibres, especially at lower basis weights. When the elastic behaviour of paper sheets is modelled, it is normally essential to know or to assume how the stresses (and strains) are distributed at the fibre level. This article presents an attempt to estimate how the stresses are transferred throughout a simple fibre network using the finite element method (FEM). Attention is mainly focused on the axial fibre stress distribution when the network is uniaxially deformed. The presence of fibre ends is found to induce local stress increases (stress concentrations) in the deformed network, which presumably have a bearing on the ultimate properties of the sheet. The influence of the properties of the bonds between crossing fibres on the mechanical properties is also investigated. It is noted that the bond stiffness has no significant effect on the stress transfer between fibres provided that the stiffness is above a critical value. Below this value the stress transfer deteriorates rapidly.     

High performance dehydration of ethyl acetate/water mixture by pervaporation using NaA zeolite membrane synthesized by vacuum seeding method

High quality NaA zeolite membranes were prepared by vacuum assisted secondary growth. At the first stage in which NaA powder was synthesized, increasing the aging time led to formation of impure and smaller crystals. However, at the aging time of 48 h, pure NaA zeolite particles with average particle size of 1.5 μm were obtained. In the second stage, the outer surface of porous α-Al₂O₃ tubular supports were seeded by vacuum method using 1.5 μm NaA particles. The most stable and uniform seeded layer was obtained at seeding time and suspension concentration of 90 s and 5 g L⁻¹, respectively. Then, 6 h of secondary growth of the zeolite layer on the seeded surface was carried out at 373 K three times. The XRD and SEM results showed the formation of a uniform and dense layer of pure NaA zeolite with an average thickness of 45 μm. Dehydration experiments were conducted on ethyl acetate/water mixtures with 2 wt% water content. The average total fluxes were 0.147, 0.208, and 0.315 kg m⁻² h⁻¹ at 303, 313, and 323 K, respectively. The separation factor was 163,000. This parameter did not change with temperature and it was due to very close activation energies of ethyl acetate and water.     

用原子力显微镜研究纤维素膜表面形貌和孔径大小及分布

介绍了原子力显微镜 (AFM )的测试原理和用于纤维素膜测定的方法 ,测定了几种纤维素膜的表面形貌 .结果表明 :AFM非常适合用于研究纤维素膜表面形貌结构 ;通过分析纤维素膜表面孔径大小和分布 ,可以较好地解释纤维素膜性能的变化     

Release behavior and kinetic evaluation of berberine hydrochloride from ethyl cellulose/chitosan microspheres

Novel ethyl cellulose/chitosan microspheres （ECCMs） were prepared by the method of w/o/w emulsion and solvent evaporation. The microspheres were spherical, adhesive, and aggregated loosely with a size not bigger than 5 pm. The drug loading efficiency of berberine hydrochloride （BH） loaded in microspheres were affected by chitosan （CS） concentration, EC concentration and the volume ratio of V（CS）/V（EC）. ECCMs prepared had sustained release efficiency on BH which was changed with different preparation parameters. In addition, the pH value of release media had obvious effect on the release character of ECCMs. The release rate of BH from sample B was only a little more than 30% in diluted hydrochloric acid （dHCl） and that was almost 90% in PBS during 24 h. Furthermore, the drug release data were fitted to different kinetic models to analyze the release kinetics and the mechanism from the microspheres. The released results of BH indicated that ECCMs exhibited non-Fickian diffusion mechanism in dHCI and diffusion-controlled drug release based on Fickian diffusion in PBS. So the ECCMs might be an ideal sustained release system especially in dHCl and the drug release was governed by both diffusion of the drug and dissolution of the polymeric network.     

聚乳酸/乙基纤维素复合膜的制备及其性能

以烯基琥珀酸酐( ASA) 作为新型增塑剂, 使用三氯甲烷作为聚乳酸( PLA) 和乙基纤维素( EC) 的共溶剂, 采用溶液浇铸法成功制备了聚乳酸/ 乙基纤维素复合膜。用红外光谱( FT IR) 、X 射线衍射(XRD) 表征了复合膜结构, 并测试了其吸水性和力学性能。FTIR 测试结果显示, 复合膜中存在强烈的氢键相互作用。XRD 表明,ASA 显著提高了PLA 和EC 2 种高聚物的界面黏合性。力学测试结果表明, ASA 对该复合膜具有良好的增塑效果。当膜中PLA 质量分数[ 37%时, PLA 对复合膜起增强作用。复合膜的吸水性随ASA 含量的增大而降低, 随PLA 含量的增大而提高。该复合膜作为一种潜在的药物缓释材料, 将具有广阔应用前景。      

乙基纤维素与聚L-乳酸接枝共聚物的合成与表征

以辛酸亚锡为催化剂,乙基纤维素(EC)为接枝骨架,L-丙交酯(L-LA)为接枝单体,在无溶剂条件下本体聚合制备了乙基纤维素-聚L-乳酸接枝共聚物。利用GPC,FTIR,1H NMR对接枝共聚物进行表征。结果表明,L-丙交酯在乙基纤维素残存的羟基上发生开环聚合,将聚乳酸短链引入到乙基纤维素骨架上,所得产物为乙基纤维素与聚L-乳酸接枝共聚物。XRD和偏光显微镜(POM)分析表明,当接枝率大于等于252%时,接枝共聚物开始结晶。     

NMMO法纤维素膜的结构与性能

以纤维素为原料，NMMO为溶剂，用相转化法制备超滤膜，并研究了浆粕种类，铸膜液浓度，凝固浴浓度，温度对膜性能和结构的影响，同时对成膜机理也进行了探讨。     

纤维素/CdS纳米复合材料的声化学制备及其光电性能

以无水氯化镉和硫化钠为原料,微晶纤维素MCC为模板,采用声化学法成功制备MCC/CdS纳米复合材料.用原子力显微镜(AFM),X射线衍射(XRD),荧光光谱(PL)以及光电化学实验对复合材料的结构及性能进行表征.研究表明,粒径为30-70nm的CdS粒子均匀分布于微晶纤维素表面,所得CdS粒子为立方型晶体.PL光谱分析...     

Titanium dioxide/cellulose nanocomposites prepared by a controlled hydrolysis method

TiO₂/cellulose nanocomposites were prepared through the titanyl sulphate hydrolysis in acidic medium in the presence of cellulosic fibres. The influence of several reaction parameters on the morphological characteristics of the nanocomposites was investigated. There is evidence from this study that in specific experimental conditions, the cellulose fibres promote the nucleation and growth of TiO₂ particles, yielding hybrid materials containing up to 46% TiO₂. Two series of paper handsheets having distinct TiO₂ content have been prepared, one from a selected hybrid composition and the other from mixtures of commercial TiO₂ and cellulose fibres. Comparative optical studies performed on the paper handsheets revealed a much higher opacity for the synthetic sample.     

乙基纤维素/C60复合膜制备及气体分离性能研究

为制备C60含量不同的乙基纤维素(EC)/C60复合膜,采用UV-可见光谱、AFM和XRD等手段对紫外光辐照前后复合膜结构进行表征,并考察其对气体分离及渗透性能的影响.结果表明,复合膜经紫外光辐照后,C60在膜表面的分布由独立的簇状结构转变为连续平缓的丘陵状结构,膜表面更加致密光滑;复合膜分子链间距未发生明显变化,但对N2、CO2、H2的渗透性能和H2/N2、CO2/N2分离性能产生明显影响.当C60添加量达到1.6%时,未经紫外光辐照的复合膜对CO2及H2的透气系数较纯EC膜分别提高了30%和40%,分别达到61.29Barrer和78.88Barrer,对H2/N2,CO2/N2理想分离系数增至纯EC膜的1.47和1.38倍,分别达到9.979和12.84;经紫外光辐照后,高C60含量的EC/C60复合膜能够保持纯EC膜对CO2和H2的透过水平,而对H2/N2和CO2/N2的分离性能增至纯EC膜的2.30和2.43倍,分别达到17.49和25.60.     

Controlled-release behavior of diphenhydramine hydrochloride loaded neutral microgranules and coated using ethylcellulose water dispersion

The development of a loading method of a water-soluble drug using aqueous binding solution to produce microgranules that were then coated with an aqueous ethylcellulose dispersion to sustain drug release is described. The results, in terms of drug used, showed that besides the fluidized bed parameters, the amount of drug dissolved in the binder solution plays an important role in obtaining a satisfying result during the spraying process. Thus, it seems necessary to determine the critical concentration above which the material started to adhere to the interior of the fluidization column, and the possibility of drug layering onto carrier material is aggravated. ANOVA of the time parameter for release of 63.2% of total drug (td) value showed significant influence of ethylcellulose (Aquacoat ECD-30) and dibutyl sebacate concentration on diphenhydramine hydrochloride (DPH) release. The dissolution rate decreased with an increase in polymer concentration. The diffusional exponent n of the Peppas equation indicated that the DPH release kinetic was non-Fickian but approached Fickian diffusion, particularly at higher coating levels.     

溶剂法纤维素膜的制备改性与气体渗透性能

以N-甲基吗啉-N-氧化物（NMMO）为溶剂物理溶解纤维素，是纺织行业中新兴的Lyocell纤维制备过程中采用的溶解方法．本实验室创造性地借鉴此工艺。以NMMO为溶剂制备出新型纤维素膜．本文介绍了纤维素作为膜材料的优点以及溶剂法新型纤维素膜的制备、干燥、改性以及气体渗透性能等．     

Preparation of ethyl cellulose pseudolatex and studies on suitability of it as a binder for granulation

Ethyl cellulose pseudolatices were prepared by an emulsion-solvent evaporation technique, which consisted of dissolving the polymer in a blend of benzene and ethyl alcohol, followed by the addition of adjuvants. The organic, solvents were removed from the emulsion using vacuum distillation. Physical evaluation of the dispersions and the cast films was carried out.

On the basis of characteristics of cast films selected formulations were fused as granulating agents for preparing chlorpheniramine maleate tablets. Good correlation was observed between total solid in the granulating dispersion and the drug release. The possible mechanisms for the drug release from the tablets are suggested.     

Biodegradable electrospun nanocomposite fibers based on Poly(2-hydroxy ethyl methacrylate) and bamboo cellulose

Electrospun fibers resemble extracellular matrix and are successfully being used in drug delivery and wound healing. The present study reports the extraction of cellulose from natural fiber such as bamboo which is cost effective. It was then added to Poly(2-hydroxy ethyl methacrylate) (pHEMA) solution and electrospun to obtain pHEMA-bamboo cellulose nanocomposite fibers. The characterization of the prepared bamboo cellulose, pHEMA-bamboo cellulose nanocomposite fibers were carried out using FTIR, XRD, TGA and SEM analysis. The biocompatibility of the prepared nanocomposite fiber were studied by MTT extraction method using Vero cell lines. Similarly the anticancer activity of paclitaxel incorporated nanocomposite fibers were assessed using MCF 7 cancer cell lines. The prepared nanocomposite fibers showed 96% cell viability and the paclitaxel incorporated pHEMA-bamboo cellulose nanocomposite fiber showed 7.4% cancer cell viability in 72 h. This proves the applicability of the prepared polymer matrix composite fiber as a fibrous mesh covering the affected skin area for skin cancers or wound healing.     

气相色谱-质谱法测定醋酸纤维滤棒中的苯系物

建立了气相色谱-质谱法测定醋酸纤维滤棒中苯系物的方法.样品以正戊烷萃取,用对溴氟苯作为内标,以DB-WAXetr柱分离,用选择离子方式检测,以标准加入法定性、内标法定量进行检测.方法在0.005～0.1 μg/mL范围内具有良好的线性关系,拟合度为0.992 9～0.9995,检出限为0.010～0.025 μg/g;样品的RSD≤6.1％,回收率为94.1％～96.6％.结果表明:该方法能够快速、准确地测定醋酸纤维滤棒中的苯系物.