溶剂散逸自组装制备高分子有序微透镜阵列

利用水珠为模板制备了聚苯乙烯有序多孔膜.在溶剂挥发的制冷作用下,水珠能够在冷的高分子溶液表面凝结形成有序的阵列,溶剂蒸发完毕后,高分子材料按照水珠排列形貌空隙形成有序多孔膜,一种两性共聚物被加入到溶液中稳定水珠而获得有序的多孔结构. 将聚乙烯醇水溶液填充入多孔膜中,蒸干后用氯仿洗去聚苯乙烯,得到聚乙烯醇的整球微透镜阵列. 聚苯乙烯有序针垫阵列是由有序多孔膜撕掉上层制备的,这种针垫结构内部具有半球结构的空间,并以此为模板制备了聚乙烯醇半球微透镜阵列. 2种微透镜阵列均具有微观显影功能. 通过2种微透镜的显像对比证实,半球微透镜阵列比整球微透镜阵列具有更为清晰的多重显像效果.     

利用酸敏感超支化聚缩醛制备聚乳酸多孔微球

通过缩醛转移聚合合成了一种具有酸敏感特性的超支化聚缩醛(HBPAs),对该聚合物降解行为的研究表明,该聚合物具有很强的酸敏感特性,在pH为5.0时,短时间内可发生迅速的降解,而在pH为7.4时,该聚合物基本不发生降解.利用该聚合物的酸敏感特性,其在弱酸性条件下降解速率远远超过PLA的降解速率,制备了多孔PLA微球.进一步研究发现,通过调控超支化聚缩醛(HBPAs)与PLA的投料比,可以线性调控PLA多孔微球的孔径尺寸,并拟合得到了线性方程.DSC结果以及对微球降解过程的观察表明,在共混微球内部,HBPAs与PLA会发生一定的相分离,使得在酸降解的过程中,更有利于微球内部的HBPAs组分发生降解.     

聚己二酸丁二酯纳米纤维构建的微球的制备

建立了采用异相成核和可控水解相结合的方法制备由纳米纤维构建的聚合物微球的新方法.根据多取代卞叉山梨醇(TM6)对聚己二酸丁二酯(PBA)的异相成核作用以及结晶形态的影响,采用两种乳液溶剂挥发法、并在聚合物溶液中加入成核剂TM6制备了PBA微球,研究了成核剂含量对PBA微球在酶促降解之后形态变化的影响.研究结果表明,二次乳液溶剂挥发法可以制备具有多孔结构的PBA微球,这种多孔结构有利于酶溶液进入到微球内部,促进PBA微球的均匀水解,最终获得由PBA纳米纤维构建的微球.当TM6的含量为3 wt%时,采用二次乳液溶剂挥发法制备的PBA微球,经过5 h酶促降解处理,可以得到表面和内部由PBA纳米纤维均匀组成的微球.进一步的细胞实验表明,微球的纳米纤维结构,有利于MG-63细胞在聚合物微球上的黏附、铺展和向内生长.     

超临界技术制备多孔聚合物微球及其应用

多孔聚合物微球被广泛应用在生物技术、医学工程、环境工程、食品安全、色谱填料等领域,因此受到材料科学家的广泛关注.超临界技术是一种廉价的绿色致孔技术,在多孔聚合物微球的制备方面具有广阔的发展前景.经悬浮聚合、乳液聚合、种子聚合、沉淀聚合等多种聚合方法合成聚合物微球,通过超临界干燥技术除去溶剂实现致孔,可得到高质量多孔聚合...     

不同浸润性多孔电极表面的气泡行为

采用氢气模板法制备了具有多孔结构的电极; 通过改变电镀电流密度和电镀时间实现了电极表面多孔结构孔径和分布的控制; 通过改变表面化学组成有效调控了电极表面的浸润性质. 比较了具有不同微观结构和表面化学组成的电极在给定条件下电解水过程中气泡的产生及行为机制. 实验结果表明: 相对于亲水的多孔电极, 疏水的多孔电极表面能够黏附气泡, 更易倾向于形成稳定的气膜; 多孔结构对于亲水电极表面气泡行为的影响比对疏水电极表面气泡行为的影响更为显著; 与没有多孔结构的亲水电极相比, 具有多孔结构的亲水电极表面产生的气泡数量多, 速率快; 与较小孔径的多孔亲水电极相比, 较大孔径的多孔亲水电极表面产生气泡速率快且黏附气泡数量少. 该研究结果为微气泡减阻电极的设计提供了理论依据.     

相反转乳化技术制备环氧树脂交联多孔微球

多孔微球在分离吸附、催化、涂料印刷等多方面具有潜在应用价值 .最近研究表明 ,当微孔孔径在 2 0 0～ 80 0ｎｍ范围时 ,由于强烈的光散射作用 ,多孔微球可以作为遮光剂使用[1] .Ｏｋｕｂｏ等用酸碱逐步处理法制备了一些共聚物的亚微米级多孔球[2～ 4] .Ｏｋｕｂｏ又用动态溶胀种子聚合法制备了微米级的聚合物微球 ,用类似的方法得到了多孔结构[5,6] .但这种方法涉及了许多烦琐过程并且产生了很多副产物需要处理 ,使得其费时费力而且成本相当高 .Ｓｃｈｌａｒｂ等发展了一种新的制备方法 ,在乳液聚合过程中引入有机溶剂 ,在实验后期除掉有机…     

以多孔CaCO3微球为模板制备聚乙烯超疏水表面

以聚苯乙烯磺酸钠（PSS）掺杂的多孔碳酸钙（CaCO3）微球层为模板,通过热压低密度聚乙烯（LDPE）并结合酸蚀刻的方法制得了具有多层粘联微球结构、而非常见蜂窝状多孔结构的LDPE稳定超疏水表面（接触角152.8±2.5°,滚动角约6°）。元素分析表明,表面粘联微球为纯LDPE而非LDPE包覆的CaCO3。将多孔CaCO3微球稀疏地撒在LDPE表面并加热熔融,发现微球会自发沉降到熔体内部,酸蚀刻后形成了类似莲蓬的表面微结构,即坑内包含小球。结合CaCO3微球生成原理和多孔结构,认为粘联微球结构和莲蓬结构均是由于LDPE熔融大分子自发沉积到多孔CaCO3微球内部,“反模”形成了LDPE微球所致。本发现为多孔CaCO3微球的应用开辟了新方向。     

PLA/MSM缓释微球的制备及生物活性

采用膜乳化-液中干燥法制备出担载二甲基砜(MSM)的聚乳酸(PLA)微球(PLA/MSM), 并研究了膜孔径、 搅拌转速和MSM浓度对载药微球形貌、 尺寸、 载药量、 体外释放及细胞活性的影响; 采用场发射环境扫描电子显微镜(ESEM)观察微球形貌、 尺寸及分布, 用等离子体发射光谱(ICP-AES)法检测PLA/MSM微球载药量、 包封率及体外释放, 采用ESEM观察微球内部结构, 并通过体外细胞培养和噻唑蓝(MTT)法检测MC-3T3-E1细胞的增殖能力. 研究结果表明, 膜乳化法制备的载药微球规整, 呈典型的圆球状, 表面光滑, 内部有多孔结构. 当膜孔径为5.1 μm且搅拌转速为500 r/min时, PLA/MSM微球大小更为均一; 当体系中MSM质量分数为8.6%时, 载药量可达到77.43%. 随着膜孔径减小及药物浓度的增加, 体外释放速率加快, 但初期均无明显的突释现象, 约10 d后累积释放量达到89.2%. 细胞实验结果显示, 在膜孔径为5.1 μm且MSM质量分数为8.6%的条件下, 制备的载药微球在细胞培养7 d时表现出明显的促增殖作用.     

不同结构Cu_2O多晶的合成及其对高氯酸铵热分解的催化作用

利用均相反应器,在没有添加剂的条件下合成了具有多孔结构的Cu2O微球.考察了合成时间以及反应器旋转速度对Cu2O微球结构的影响.通过增加聚乙烯吡咯烷酮(PVP)的用量,使得Cu2O从多孔微球转变为立方体孪晶,最终形成十四面体孪晶结构.同时,将不同结构的Cu2O多晶应用于催化高氯酸铵(AP)的热分解,结果表明:多孔Cu2O微球较其它结构的Cu2O对AP的热分解具有更高的催化活性,使得AP的低温分解温度降低了37.4°C,而AP在低温阶段的分解量也由8.7%增加至49.0%.     

壳聚糖多孔微球负载PdCl2选择性催化氢化氯代硝基苯的研究

以壳聚糖为原料，液体石蜡为分散介质，甲醛，戊二醛为交联剂，通过反相悬浮交联制备了粒径小于100μm的壳聚糖多孔微球；对制备壳聚糖多孔微球的影响因素进行了探讨，并用FTIR和SEM表征了多孔微球；XPS表明，壳聚糖多孔微球经PdCl2负载后，PdCl2与壳聚糖形成配合物，配位键是在PdCl2的Pd与壳聚糖的N之间形成。在常温常压下，PdCl2/壳聚糖多孔微球能选择性地催化还原氯代硝基苯为氯苯胺；对影响催化加氢的因素如反应温度、溶剂、催化剂用量和底物浓度作了探讨。     

Preparation of Porous Polylactide Microspheres and Their Application in Tissue Engineering

In this study,porous polylactide (PLA) microspheres with different structures were prepared through the multiple emulsion solvent evaporation method.By changing organic solvents (ethyl acetate and chloroform) and adding effervescent salt NH4HCO3 in the inner water phase,microspheres with porous capsular,matrix,microcapsular and multivesicular structures were prepared.The protein encapsulation and release,and the cell growth behavior of porous microspheres were further explored.Under the same inner water phase,microspheres prepared with chloroform had higher protein encapsulation efficiency and less protein release rate as compared with those prepared with ethyl acetate.Cell experiments showed that the relatively rough surface of microspheres prepared with chloroform was more favorable for the cell growth in comparison with the smooth surface of microspheres prepared with ethyl acetate.This study shows a simple and effective method to control the protein release and cell growth behaviors of polymer microspheres by tuning their porous structure.     

Preparation of PLGA microspheres with different porous morphologies

Poly(D,L-lactide-co-glycolide)(PLGA) microspheres were prepared by emulsion solvent evaporation method. The influences of inner aqueous phase, organic solvent, PLGA concentration on the morphology of microspheres were studied. The results showed that addition of porogen or surfactants to the inner aqueous phase, types of organic solvents and polymer concentration affected greatly the microsphere morphology. When dichloromethane was adopted as organic solvent, microspheres with porous structure were produced. When ethyl acetate served as organic solvent, two different morphologies were obtained. One was hollow microspheres with thin porous shell under a lower PLGA concentration, another was erythrocyte-like microspheres under a higher PLGA concentration. Three types of microspheres including porous, hollow core with thin porous shell(denoted by hollow in brief) and solid structures were finally selected for in vitro drug release tests. Bovine serum albumin(BSA) was chosen as model drug and encapsulated within the microspheres. The BSA encapsulation efficiency of porous, hollow and solid microspheres was respectively 90.4%, 79.8% and 0. And the ultimate accumulative release was respectively 74.5%, 58.9% and 0. The release rate of porous microspheres was much slower than that of hollow microspheres. The experiment results indicated that microspheres with different porous structures showed great potentials in controlling drug release behavior.     

Preparation of porous polylactide microspheres by emulsion‐solvent evaporation based on solution induced phase separation

Porous polylactide (PLA) microspheres were fabricated by an emulsion‐solvent evaporation method based on solution induced phase separation. Scanning electron microscopy (SEM) observations confirmed the porous structure of the microspheres with good connectivity. The pore size was in the range of decade micrometers. Besides large cavities as similarly existed on non‐porous microspheres, small pores were found on surfaces of the porous microspheres. The apparent density of the porous microspheres was much smaller than that of non‐porous microspheres. Fabrication conditions such as stirring rate, good solvent/non‐solvent ratio, PLA concentration and dispersant (polyvinyl alcohol, PVA) concentration had an important influence on both the particle size and size distribution and the pore size within the microspheres. A larger pore size was achieved at a slower stirring rate, lower good solvent/non‐solvent ratio or lower PLA concentration due to longer coalescence time. Copyright © 2005 John Wiley & Sons, Ltd.     

Structure controlling and adsorption application of polyethersulfone porous microspheres prepared via electrospraying

The focus of this work is to control the structure of electrosprayed polymer microspheres and then study the effect of different structures on the microspheres＇ adsorption properties. Scanning electron microscopy （SEM） coupled with image analysis software was employed to evaluate the size distributions and the structure of microspheres. According to the observation and analysis results, two types of polyethersulfone （PES） porous microspheres （perfect sphere-shaped and collapsed） were prepared via electrospraying technology by adjusting the solvent and polymer molecular weight. The porous PES microspheres can remove bisphenol A （BPA） from its aqueous solution effectively. Compared with collapsed microspheres, the rough microspheres had much higher specific surface area and better mobility in the BPA aqueous solution, so it showed a better adsorption capacity than that of collapsed microspheres. The solvent evaporation rate and the occurrence rate of phase separation significantly affect the structure and morphology of microspheres.     

Hydrolysis and biomineralization of porous PLA microspheres and their influence on cell growth

Poly(lactic acid) (PLA) microspheres have great potential in bone tissue engineering. However, their applications have been limited by surface and bulk properties such as hydrophobicity, lack of cell recognition sites and acidic degradation products. Apatite is a mineral which can effectively promote the adhesion and growth of bone cells. In this study, the bonelike mineral, carbonate apatite, was successfully used to functionalize porous PLA microspheres by a biomimetic mineralization method. To improve apatite formation, porous PLA microspheres were first selectively hydrolyzed in NaOH solution to increase the density of polar anionic groups on the surface, and then immersed in simulated body fluid for biomineralization. The morphology, composition, and phase structure of bioactive mineral grown on the original and hydrolyzed PLA microspheres were analyzed and compared quantitatively. The results showed that the hydrolysis which took place on the PLA microspheres enhanced the nucleation and growth of apatite. MG-63 cells attached well and spread actively on the mineralized PLA microspheres, indicating their strong potential in bone tissue engineering.     

生物可降解5-氟尿嘧啶载药微球的制备及性能研究

5-氟尿嘧啶(5-Fu)为水溶性嘧啶类抗代谢药,是治疗实体肿瘤的首选药物．但5-Fu毒性很大,血浆中停留半衰期t1／2仅为10～20min．为了减少氟尿嘧啶的毒副作用并提高药物利用率,可以将其制成聚合物载药微球．聚酯类高分子是较为常用的生物降解型药物载体材料,其中聚乳酸(PLA)及其共聚物具有良好的生物相容性及生物可降解性,常被广泛应用于药物缓释材料,     

In vitro degradation and release behavior of porous poly(lactic acid) scaffolds containing chitosan microspheres as a carrier for BMP-2-derived synthetic peptide

To develop a novel tissue engineering scaffold with the capability of controlled releasing BMP-2-derived synthetic peptide, porous poly(lactic acid)/chitosan microspheres (PLA/CMs) composites containing different quantities of chitosan microspheres were prepared by a thermally induced phase separation method. FTIR analysis revealed that there were strong hydrogen bond interactions between the PLA and chitosan component. Introduction of less than 30% CMs (on PLA weight basis) did not remarkably affect the morphology and porosity of the PLA/CMs scaffolds. The compressive strength of the composite scaffolds increased from 0.48 to 0.66 MPa, while the compressive modulus increased from 7.29 to 8.23 MPa as the microspheres' contents increased from 0% to 50%. In vitro degradability investigation indicated that the dissolution of chitosan component was preferential than PLA matrix and the inclusion of CMs could neutralize the acidity of PLA degradation products. Compared with the rapid release from CMs, the synthetic peptide was released from PLA/CMs scaffolds in a temporally controlled manner, mainly depending on the degradation of PLA matrix. The promising microspheres based scaffold release system can be used to deliver bioactive factors for a variety of non-loaded bone regeneration and tissue engineering application.     

Study of types and mixture ratio of organic solvent used to dissolve polymers for preparation of drug-containing PLGA microspheres

The effects of the types and the ratios of various organic solvents used as a mixtures to dissolve poly (lactide-co-glycolide) (PLGA) by using a solvent evaporation method, a technique used to prepare polymer particles, were carefully studied in order to investigate their advantages in developing drug delivery system (DDS) formulations for the prepared microspheres. The particle size and drug loading efficiency of drug-containing PLGA microspheres were found to be dependent on the types of solvent used due to the interfacial tension between the organic solvent and water phase. The drug loading efficiency of monodisperse microspheres prepared by using a membrane emulsification technique employing organic solvents and high interfacial tension for dissolving the PLGA was increased in a controlled manner. The organic solvents with high interfacial tension in the water phase used for the preparation of polymer particles by means of the solvent evaporation method were found to be suitable in terms of improvement in the properties of DDS formulations.     

Photocrosslinked poly(ester‐anhydride) microspheres with macroporous structure

In this work, the new method of preparation biodegradable microspheres with macroporous structure is presented. Typical methods used for generation of porous structures in microspheres obtained from preformed polymers require the use of additional substances acting as porogens. In this study, the porosity was achieved as the effect of photocrosslinking, without porogens. Microspheres were prepared using emulsion solvent evaporation technique from functional poly(ester‐anhydride)s with different amount of allyl groups in the side chains. The crosslinking was carried out by UV irradiation during the solvent evaporation (photoinitiator was introduced to polymer solution). The size of microspheres obtained was in the range of 1.7 – 4 µm (small microspheres) or 31 – 50 µm (large ones) and depended on the conditions used in emulsion formulation process. Effectiveness of the crosslinking was characterized by the content of insoluble part of samples, and it was in the range of 42–89%. The content of insoluble part of sample of microspheres and their porosity were dependent on functionality of poly(ester‐anhydride)s, the amount of photoinitiator used, and also on size of microparticles. The small particles were always more crosslinked than the large ones, but the latter were more porous than the small ones. Crosslinked microparticles indicated higher loading efficiency of model compound and appeared to degrade faster than uncrosslinked ones, probably due to their high porosity. The high porosity of microspheres obtained would enable their eventual use in pulmonary drug delivery systems or in construction of porous scaffolds for tissue engineering. Copyright © 2013 John Wiley & Sons, Ltd.     

口服聚酯聚醚疫苗蛋白微球的制备研究

采用本体聚合法合成不同聚醚含量的聚酯聚醚嵌段共聚物聚 ＤＬ 乳酸 聚乙二醇（Ｐｏｌｙ ＤＬ ｌａｃｔｉｄｅ ｂ ｐｏｌｙｅｔｈｙｌｅｎｅｇｌｙｃｏｌ,ＰＥＬＡ）．ＰＥＬＡ及ＰＬＡ包裹人血清白蛋白（ＨＳＡ）微球采用溶剂挥发法双乳液体系（Ｗ１／Ｏ／Ｗ２）制备．微球球形规整,粒径集中在０５～５０μｍ．用ＣＢＢ法检测微球中蛋白含量,蛋白包裹量达２５％,包裹效率近８０％．从双乳液体系中界面张力角度考察了聚合物囊材的性质、稳定剂的种类及Ｗ１／Ｏ的稳定性等对微球粒径及蛋白包裹量的影响．微球体外释放结果表明ＰＥＬＡ蛋白微球的突释现象不明显,释放速度较为恒定．