乳化-溶剂挥发法制备聚乳酸载药微球

采用o/w型乳化-溶剂挥发法来制备载药微球,以二氯甲烷为溶剂相,以聚乳酸为载体材料,以维A酸为包埋药物,以吐温-80和明胶为乳化剂。探索载药微球制备过程中的变量(高剪切转速、高剪切时间、内外相体积比、壁材用量等)对载药微球粒径大小、包封率以及稳定性等的影响。得出最优载药微球制备方案:明胶浓度7.5mg/mL,吐温浓度6mg/mL,聚乳酸浓度10 mg/mL,内外相体积比1∶10,剪切时间30min,搅拌速度300r/min,挥发时间3h。所制得的聚乳酸载药微球形态光滑且分散性较好,包封率为52.42%。     

改进的锐孔法制备粒径均一的聚乳酸微球

锐孔法是制备微胶囊的常用方法之一。文中根据微通道法乳化技术原理,改进了锐孔法实验装置并用于聚乳酸微球的制备;应用简化的聚乳酸微球制备模型,研究了油相注入速率、搅拌器转速、聚乳酸浓度和锐孔内径大小等因素对聚乳酸微球平均粒径d和粒径分布系数(C V)的影响。结果表明,油相注入速率小于1.2 mL/min时,对d和C V影响较小;提高搅拌器转速能降低d;随着聚乳酸浓度的增大,d和C V均呈增大趋势;当锐孔内径处于200μm~550μm时,d和C V与锐孔内径无明显关系。用内径50μm玻璃毛细管针头代替金属针头,成功地制备出粒径均一的聚乳酸微球(d=77.93μm,C V=17.59%)。     

浓度及溶剂配比对PVDF静电纺纳米纤维膜的影响

以聚偏氟乙烯(PVDF)为纺丝溶质，N,N-二甲基甲酰胺(DMF)与四氢呋喃(THF)为混合溶剂，配制不同浓度和不同溶剂配比的纺丝溶液，利用静电纺丝技术制备了PVDF纳米纤维膜。通过扫描电子显微镜(SEM)、光学接触角测量仪、ImageJ软件对所制纳米纤维膜的微观形貌、疏水性能、纤维直径等进行分析，研究了不同浓度和不同溶剂配比对纳米纤维膜的影响。结果表明：当溶液浓度为10%(PVDF质量分数),DMF/THF溶剂配比为3/2时静电纺丝制备的纳米纤维膜纤维形貌良好，直径分布均匀，具有良好的疏水效果。     

超临界流体技术制备聚合物超细微粒

以聚甲基丙烯酸甲酯为模型材料,利用近两年提出的超临界流体膨胀减压过程,成功制备出了粒径在5μm以下的超细微粒,系统分析了混合器压力和温度、溶液浓度及进液速率对微粒形态、粒径及其分布的影响。结果表明,混合器压力、溶液浓度和进液速率均对微粒粒径及其分布有明显的影响,而混合器温度的影响较小。较理想的操作条件为混合器压力为10MPa、温度为60℃、溶液浓度为10mg/mL、进液速度为3mL/min。     

超临界CO2抗溶剂法制备聚乳酸药物缓释微球

以L-聚乳酸为模型体系,超临界CO2为抗溶剂,采用超临界流体抗溶剂法制备聚乳酸微球.考察了压力、温度、溶液浓度、溶液流速、二氯甲烷-丙酮混合溶剂、聚合物分子量等参数对制备微球的形态、粒径及其分布的影响.结果表明,改变工艺参数,可在一定范围内调控微球粒径,所制微球平均粒径0.67～6.64μm,溶液浓度及其流速为主要影响因素;实验条件一定时,采用二氯甲烷-丙酮混合溶剂及强制分散溶液法制备得较小粒径微球.释放度实验结果表明,微球按一级释放方程释药,具缓释效果.     

高比表面积多孔二醋纤超细纤维的制备研究

借助高挥发溶剂引发的热致相分离原理,以二氯甲烷/丙酮为溶剂,通过静电纺丝技术制备二醋酸纤维素多孔超细纤维。通过正交试验,对影响二醋酸超细纤维比表面积的5个主要因素(溶剂配比、溶液浓度、纺丝电压、接收距离和纺丝速度)在4个水平上进行了优化筛选。以纤维的比表面积为考察目标,获得了最佳纺丝工艺条件:二氯甲烷∶丙酮=7∶3,纺丝速度为1mL/h,接收距离为10cm,纺丝电压为24kV,纺丝浓度为3.5%(质量分数)。在5个因素中,溶剂配比对纤维比表面积的影响最为显著。且经过优化,最终得到了比表面积为(23.1694±0.3256)m~2/g的多孔超细二醋酸纤维。     

同轴电喷射法制备核壳结构聚乳酸载药微球

通过同轴静电喷射法制备核-壳结构聚乳酸载药微球。壳层流体为聚乳酸溶液,核层流体为药物水溶液,其中在核层流体中加入壳聚糖以达到在增加溶液电导率的同时改善聚乳酸的亲水性和功能性的目的。实验研究了核、壳层溶液浓度、流量、喷射电压以及接收距离等因素对微球形貌及结构的影响。研究结果表明,当控制实验条件为壳、核层流速比为3∶1,壳层溶液浓度与核层溶液浓度均为1%(质量浓度),喷射电压为20kV,接收距离为15cm,模型药物浓度2mg/mL时,可以得到粒径1μm左右、具有一定缓释效果的核壳结构载药微球,包封率为76.64%,载药量为7.11%。     

混合溶剂沉淀聚合工艺制备AN/AM/IA三元共聚物研究

以偶氮二异丁脒盐酸盐(V50)为引发剂,采用水/二甲基亚砜(H_2O/DMSO)混合溶剂沉淀聚合工艺合成了高分子量的丙烯腈/丙烯酰胺/衣康酸(AN/AM/IA)三元共聚物。用乌氏黏度计测出产物的平均分子量,继而分析了引发剂浓度、总单体浓度、混合溶剂配比、共聚单体配比以及反应温度和时间对该聚合反应转化率和聚合物平均分子量的影响规律。结果表明:采用V50引发混合溶剂沉淀聚合工艺,可制得高产率和高分子量的PAN共聚物。     

乙二醇溶剂热法制备K_(0.5)Na_(0.5)NbO_3陶瓷粉体

采用乙二醇溶剂热法制备K_(0.5)Na_(0.5)NbO_3陶瓷粉体,系统研究了V(EG)/V(H_2O)、反应温度、前驱液浓度对粉体物相、形貌及颗粒尺寸的影响。结果表明,反应温度230℃,反应时间7h,V(EG)/V(H2O)≤3∶2可获得纯相的K_(0.5)Na_(0.5)NbO_3粉体;温度升高粉体的结晶性变差;当溶液浓度为6mol/L时,粉体出现球形和正方体两种形貌,反应物浓度增大粉体均出现正方体形貌且颗粒尺寸减小,当浓度为10mol/L、V(EG)/V(H2O)=1∶4时,粉体颗粒尺寸最小。     

肌腱仿生用定向PLLA微纳米纤维的静电纺丝工艺参数研究

采用左旋聚乳酸(PLLA)为基材研究静电纺丝工艺过程对聚乳酸纤维形貌和性能的影响,主要包括环境湿度、纺丝溶液浓度、接收转速、收集距离、注射泵推注速度、附加电压等过程参数。结果表明,接收转速与纺丝液浓度分别是影响纤维定向排列程度和纤维直径的最主要因素,其次是接收距离、环境湿度、推注速度。当聚乳酸-氯仿溶液聚合物质量浓度为80 mg/mL、纺丝电压为25 kV、接收距离为20 cm、注射泵推注速度为0.3 μL/s以及接收转速为1500 r/min时,纤维取向性良好,平均直径为(0.94±0.21) μm,可达到模拟肌腱组织天然细胞外基质结构的要求。     

A study on the electrophoretic deposition of 8YSZ coating using mixture of acetone and ethanol solvents

Electrophoretic deposition (EPD) was carried out on nickel metal sheets using acetone and ethanol mixtures. The ratios of the organic solvents in the suspension was varied to arrive at the optimum ratio of solvents and experimental conditions suitable for getting adherent and crack-free yttria-stabilized zirconia (YSZ) coatings. The volume ratios of acetone to ethanol used in the present study were 100:0 mL (4A:0E), 75:25 mL (3A:1E), 50:50 mL (2A:2E), 25:75 mL (1A:3E) and 0:100 mL (0A:4E). Iodine was used as an additive to charge the YSZ particles. The applied dc voltage was varied from 10 to 40 V cm⁻¹ and also the deposition time was varied 4, 6 and 8 min. The effect of applied dc voltage during EPD on the weight of the deposit and in turn on the thickness of the coating obtained was studied. The YSZ deposits were viewed under a metallurgical microscope to determine the presence of cracks or other defects in the as deposited coatings after initial drying. Attempts were made to understand the observed behavior of different solvent ratios with the number of protons released. This study facilitated to arrive at the optimum solvent ratio (3A:1E and 2A:2E) and the experimental conditions required for getting smooth, homogeneous, crack-free YSZ coatings by EPD on nickel substrates. Using the optimized condition of 2A:2E, lanthanum-doped strontium manganite (LSM) tube which acts as cathode in tubular solid oxide fuel cells (SOFCs) was coated with 8YSZ using EPD. The electrophoretically coated YSZ coating on sintering showed a dense microstructure.     

Supercritical fluid extraction of natural antioxidants from rosemary: comparison with liquid solvent sonication

Supercritical fluid extraction (SFE) and liquid solvent sonication, in combination with two different sample treatments, were compared for the extraction of natural antioxidants from rosemary leaves. Dried, ground, and sieved rosemary leaves (20 mg) were subjected to SFE with CO(2) at 355 bar at 100 °C (CO(2) density 0.72 g/mL) for 20 min at a liquid flow rate of 4 mL/min. The analytes were concentrated on an ODS trap and subsequently eluted with acetone. Antioxidants in the SF and liquid solvent extract were analyzed by HPLC. Compounds of known antioxidant activity such as carnosol, carnosic acid, and methyl carnosate were identified by mass spectrometry of the HPLC fractions collected. Freezing and grinding the samples in liquid nitrogen resulted in decreased carnosic acid recoveries. Supercritical CO(2) extraction provided the highest recovery of carnosic acid from rosemary leaves (35.7 mg/g), the lowest relative standard deviation (4.4%), and the cleanest extract [Formula: see text] no cleanup prior to HPLC was required. Among the liquid solvents studies, only acetone provided comparable results (73% recovery relative to SC-CO(2) extraction); however, it required decoloration with active carbon prior to HPLC analysis.     

Size control for fullerene C60 nanocrystals during the high temperature and high pressure fluid crystallization process

The preparation and size control for mono-dispersed fullerene C₆₀ fine particles was successfully achieved during the high temperature and high pressure fluid (HTPL) crystallization process, in which acetone was used as the HTPL solvent and pure water or the mixture of acetone and water as the cooling solvent. The prepared fullerene C₆₀ particles had spherical shape and narrow size distribution with the average size ranging from 44 nm to 110 nm depending on the various experimental conditions, such as fluid temperature, solvent flow rate, system pressure and the ratio of acetone and water in cooling solvent. The products were characterized by using X-ray powder diffraction (XRD), scan electron microscopy (SEM), dynamic light scattering technique (DLS) and UV–VIS spectrum, respectively. And the size effect of such fullerene C₆₀ nanocrystals was confirmed.     

Preparation and physicochemical characterization of soy isoflavone (SIF) nanoparticles by a liquid antisolvent precipitation method

Soy isoflavone (SIF) nanoparticles were prepared using dimethyl sulfoxide as a solvent and water as an antisolvent. Response surface methodology was used to analyse the influences of several process parameters on the mass median diameter (D50). The SIF concentration (20–40 mg/mL), volume ratio of antisolvent to solvent (5–7 mL/mL), stirring speed (800–1600 r/min), and reaction time (2–4 min) were optimized. The optimal conditions were determined to be a SIF concentration, volume ratio of antisolvent to solvent, stirring speed and reaction time of 29 mg/mL, 7 mL/mL, 1533 r/min and 3 min, respectively. Satisfactory D50 of SIF (101.24 ± 12.21 nm) were achieved. The processed and unprocessed SIFs were tested and characterized. By comparing the parameters, the chemical properties of the processed and unprocessed SIFs did not change, but the water dissolution rate of the prepared SIF nanoparticles was greatly enhanced.     

Crystallization of progesterone polymorphs using polymer-induced heteronucleation (PIHn) method

Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications.     

Preparation and characteristics of carbon-supported platinum catalyst and its application in the removal of phenolic pollutants in aqueous solution by microwave-assisted catalytic oxidation

Granular activated carbon-supported platinum (Pt/GAC) catalysts were prepared by microwave irradiation and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Pt particles dispersing onto the surface of GAC could be penetrated by microwave and acted as "reaction centre" in the degradations of p-nitrophenol (PNP) and pentachlorophenol (PCP) in aqueous solution by microwave-assisted catalytic oxidation. The reaction was carried out through a packed bed reactor under ambient pressure and continuous flow mode. Under the conditions of microwave power 400 W, influent flow 6.4 mL min(-1) and air flow 120 mL min(-1), phenolic solutions with high concentration (initial concentrations of PNP and PCP solutions were 1469 and 1,454 mg L(-1), respectively) were treated effectively by Pt/GAC, 86% PNP and 90% PCP were degraded and total organic carbon (TOC) removal reached 85% and 71%, respectively. Compared with GAC, loaded Pt apparently accelerated oxidative reaction so that Pt/GAC had a better degrading and mineralizing efficiencies for PNP. Hydraulic retention time was only 16 min in experiment, which was shortened greatly compared with catalytic wet air oxidation. Pyrolysis and oxidation of phenolic pollutants occurred simultaneously on the surface of Pt/GAC by microwave irradiation.     

Enhanced water-solubility of Licorice extract microparticle prepared by antisolvent precipitation process

In this study, Licorice extract (LE) microparticles were successfully prepared using antisolvent precipitation process. Ethyl acetate and dimethyl sulfoxide, were used as the antisolvent and solvent, respectively. By means of orthogonal experimental design, the influences of several process parameters on the mean particle size (MPS) were investigated. The concentration range of the LE solution, the volume ratio of solvent to antisolvent, dripping speed, and temperature were 4.3–34.5 mg/mL, 1:1–1:12, 1–10 mL/min, and 20–35 °C, respectively. Based on the above orthogonal experiments, the optimum antisolvent precipitation process conditions were found to be: temperature 20 °C, concentration of the LE solution 17.2 mg/mL, volume ratio of solvent to antisolvent 1:4, dripping speed 10 mL/min. The LE microparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), HPLC analysis and dissolution test. And the morphology, crystalline state and chemical structure, drug purity, dissolution rate and bioavailability of LE microparticles were investigated. Under optimum antisolvent precipitation process conditions, the MPS of LE microparticles reached to 85.3 nm, and with uniform distribution. And the LE microparticles had the same chemical structure as the unprocessed drug, but the crystallinity was reduced, purity was increased. Furthermore, the water solubility increased from 4.82 mg/mL to 16.10 mg/mL, and bioavailability is increased by 64.36%.     

Carboxyl-functionalized superparamagnetic Fe3O4/poly(St-co-MPS)/SiO2 composite particles for rapid and sensitive immunoassay

Superparamagnetic Fe3O4/poly(St-co-MPS)/SiO2 composite particles with the average size of 140 nm were functionalized with carboxyl group by emulsion polymerization. Functionalized particles with carboxyl contents of 13.6 and 136 micromol/mL were prepared by changing the amount of acrylic acid monomer used in the polymerization. After conjugation with human chorionic gonadotrophin (hCG) antibody, the particles were used to construct lateral flow immunoassays (LFIA) for the detection of hCG in solution. The quantitative analysis could be finished in 20 min by using the magnetic particles as labels. The detection limit of LFIA was determined to be 1 and 5 IU/L respectively for the magnetic particles with carboxyl contents of 13.6 and 136 micromol/mL.     

Preparation of monodispersed spherical barium titanate particles

Spherical barium titanate particles with cubic phase were synthesized by a low-temperature hydrothermal reaction. Firstly, The method of hydrolysis of titanium tetrachloride was used for producing spherical TiO₂ particles (0.45–1.5 μ m) with various concentrations of TiCl₄(0.05–0.2 M) and volume ratios of acetone to water solutions (RH = 0–4). These TiO₂ particles were converted to barium titanate by a hydrothermal conversion in a barium hydroxide solution. The size and morphology of the TiO₂ particles was controlled by the volume ratio of acetone to water (RH ratio) in the mixed solvent. At the RH ratio of 3, the morphology of TiO₂ particles was very uniform and discrete. These TiO₂ particles were in the anatase phase and were converted to the rutile phase when the calcination temperature increased to 700∘C and above. Uniform and spherical barium titanate particles were successfully synthesized from the as-prepared TiO₂ particles by using a hydrothermal reaction in a barium hydroxide solution. The Ba/Ti ratios, reaction temperature, and reaction time did not influence the size and morphology of BaTiO₃ particles, but increased the concentration of unfavorable salts such as Ba(OH)₂ and BaCO₃. The high purity BaTiO₃ particles could be obtained by washing with formic acid to remove the unfavorable salts. The size and morphology of the BaTiO₃ particles remained the same as those of the TiO₂ particles, confirming the in-situ transformation mechanism for the conversion of TiO₂ to BaTiO₃. The as-synthesized particles were cubic phase and transformed to tetragonal phase after calcinations at 1150∘C for 1 h. The mean density of the pellets sintered at 1300∘C for 2 h was 5.86 g/cm³ and accounted for 97.34% of the theoretical density.     

Effect of the solvent on the particle morphology of spray dried PMMA

The effect of various solvents on the morphology of polymethyl methacrylate (PMMA) particles synthesized by spray drying is examined. It is concluded that the product PMMA particles, derived from the PMMA-acetone dilute solution, have a smaller particle size than those from the PMMA-THF dilute solution. This is due to the stronger PMMA-acetone interaction, since acetone is a good solvent for PMMA, while THF is a poor solvent for PMMA. By controlling the temperature of each section of the tube furnace, the heating rate was adjusted so that both solid and hollow particles could be obtained. When water was added to these dilute solutions, porous or honeycomb particles were produced due to the different evaporation rates of solvent and water. This was a result of a large difference in the solubility parameter values between PMMA and solvent. The strong interaction between PMMA and acetone results in the formation of porous particles while the weak interaction between THF and PMMA produced honeycomb structure particles.