磁性聚苯乙烯微球的合成和特性

本文报导了磁性聚苯乙烯微球的合成和特性。采用改进了的乳液聚合法,在磁流体存在下进行苯乙烯、二乙烯基苯和丙烯酸的三元共聚,可得到含0.067％Fe_3O_4、平均拄径为0.06～0.7μm的磁性聚苯乙烯微球。该微球外观呈球形,内部为多相构造,可在磁场下被分离出来。微球粒径分布窄,具有良好的机械稳定性和耐酸性。实验表明,引发剂和乳化剂用量减少,微球粒径增大;分散介质中乙醇含量对磁性聚苯乙烯微球的形成有很大影响,增加乙醇含量可使微球粒径达到1mm。     

磁性聚乙烯醇微球的制备及其性质

采用分散聚合法，在Fe3O4磁流体存在下，通过PVA分子单体共聚制备磁性高分子微球。用透射电镜和X射线对磁流体的形貌、粒径进行表征和衍射分析，同时借助于显微拍照和红外光谱，对磁性微球的微观形貌和化学成分进行了研究。通过对比磁性微球的磁响应性及粒径，研究了反应温度、搅拌速度、聚乙烯醇用量、盐酸用量等操作因素对磁性微球性质的影响。结果表明，在70℃操作温度、750r／min的搅拌速度，5ml9％PVA和0．5ml37%盐酸条件下能制备出粒径在8～44μm之间、具有良好磁响应性、表面富含羟基和羧基等官能团的磁性聚乙烯醇微球。     

蔗糖/水体系磁性聚苯乙烯微球的制备及其表征

以氧化法制备Fe_3O_4磁流体,首次采用蔗糖水溶液为分散介质,以聚乙烯醇为稳定剂,偶氮二异丁腈为引发剂,悬浮聚合法合成了磁性聚苯乙烯微球.该蔗糖水反应体系对环境无污染且后处理简单.考察了蔗糖、苯乙烯(St)、Fe_3O_4磁流体、稳定剂、引发剂的含量等条件对微球的粒径及其分布的影响.所合成的磁性聚苯乙烯微球具有核壳型结构,有较强的磁响应性能,球形和分散度良好,粒径为80～85μm.采用红外光谱、振动样品磁强计和光学显微镜对磁性聚苯乙烯微球进行了表征.     

具有磁导向性的交联β-环糊精聚合物微球的合成与性能

以经乳化剂修饰过的Fe3O4为核,环氧氯丙烷为交联剂,采用分散聚合法,合成了粒径为1.28～4.15μm、分散性较好、磁含量(Fe3O4)达68%的磁性交联β-环糊精聚合物微球.讨论了各种因素对合成条件的影响,对所得磁性微球的外观形态、磁响应性进行了表征,结果表明,该磁性微球可作为靶向药物载体.     

免疫磁性微球的制备及其在丙肝病毒检测中的应用

采用悬浮-乳液聚合法合成了超顺磁性聚丙烯酸甲酯微球,通过氨解反应在微球表面修饰了氨基并偶联了丙肝抗体,通过硅烷化反应在载玻片上修饰了氨基并偶联了丙肝抗体。采用振动样品磁强计（VSM）、生物显微镜和原子吸收光谱仪（AAS）对合成的磁性微球进行了表征。结果表明微球尺寸均一,单分散性较好,平均粒径为4μm,比饱和磁化强度为7.181A.m2/kg,微球表面氨基浓度为0.433mmol/g,具有超顺磁性。通过微球表面的抗体和载玻片上的抗体与丙肝抗原的免疫反应检测丙肝病毒,阴、阳性得到了很好的区分,达到了较好的检测效果。     

磁性聚乙烯醇微球的制备及其性质

采用分散聚合法,在Fe3O4磁流体存在下,通过PVA分子单体共聚制备磁性高分子微球.用透射电镜和X射线对磁流体的形貌、粒径进行表征和衍射分析,同时借助于显微拍照和红外光谱,对磁性微球的微观形貌和化学成分进行了研究.通过对比磁性微球的磁响应性及粒径,研究了反应温度、搅拌速度、聚乙烯醇用量、盐酸用量等操作因素对磁性微球性质的影响.结果表明,在70 ℃操作温度、750 r/min的搅拌速度,5ml 9%PVA和0.5 ml 37%盐酸条件下能制备出粒径在8～44 μm之间、具有良好磁响应性、表面富含羟基和羧基等官能团的磁性聚乙烯醇微球.     

具有pH值敏感的磁性β-环糊精微球的制备与性能

采用反相乳液聚合法,由改性磁性Fe3 O4纳米粒子、β-环糊精(β-CD)、丁二酸酐(SA)制备了具有pH值敏感的β-环糊精磁性微球;通过红外光谱、透射电镜对微球进行了结构表征和形貌观察,并探讨了微球的pH值敏感性和磁响应性能.结果表明:制备的β-CD微球为核壳结构,粒径为20μm左右,具有良好的磁性和pH值敏感性.     

聚(苯乙烯-丙烯酸)磁性高分子微球的制备及性能

以苯乙烯为单体、丙烯酸为功能基单体、N,N′-亚甲基双丙烯酰胺为交联剂,加入自制的纳米Fe3O4磁流体,采用分散聚合的方法制备出聚(苯乙烯-丙烯酸)磁性高分子微球。采用XRD、FT-IR、SEM、752N型分光光度计和化学滴定法,对所制得的磁性高分子微球进行了表征及性能分析,研究了交联剂N,N′-亚甲基双丙烯酰胺的加入对其性能的影响。结果表明,所制磁性微球粒径在0.7μm~2 m之间,单分散性好;交联剂对微球性能有着明显的影响,随着交联剂的增加,微球粒径变小、粒径分布变宽、表面羧基含量增加、耐酸碱性增强,最佳含量应为单体用量的4%。     

悬浮聚合法制备聚苯乙烯磁性微球

本文以聚乙烯醇/水为介质,苯乙烯为单体,在经3-甲基丙烯酰氧基丙基三甲氧基硅烷(3-MPS)表面修饰的Fe3O4磁性颗粒的存在下,采用悬浮聚合法,制备了聚苯乙烯磁性微球。分别用X-射线衍射(XRD)、原子力显微镜(AFM)、热重分析(TGA)、傅里叶变换红外光谱仪(FTIR)、振动样品磁力计(VSM)等方法对磁性微球的结构和性能进行了表征。实验结果表明,所合成的磁性微球为球型结构,平均粒径约为2μm,尺寸分布较均匀,具有超顺磁性。     

亲水性磁性微球的制备与表征

为了获得表面亲水性的磁性微球，在用微乳液法制备聚苯乙烯（PSt）的过程中，引入聚合单体甲基丙烯酸（MAA），得到P（St-MAA）磁性微球。通过光学显微镜、接触角测量仪、傅立叶红外测量仪和振动磁强计对该微球的性质进行了分析。结果表明该微球粒径大小分布在1～5μm之间，矫顽力和剩磁为0，具有很好的超顺磁性，表面含有羧基基团，与水珠的接触角为70°，表现出良好的亲水性。     

以明胶为模板制备复合空腔微球

以明胶微球为模板, 采用层层自组装技术制备了明胶/SiO₂/PAH复合微球, 并用热水溶解模板得到了SiO₂/PAH复合空腔微球. 通过用ζ电位、TEM、IR、TG等测试手段对其样品进行表征分析. 结果表明, SiO₂/PAH有效地组装在明胶微球上, 形成了核壳式结构, 模板去除后得到空腔结构. 在溶解模板的过程中, 通过对明胶水解产物氨基酸含量的测定, 发现SiO₂/聚电解质的存在具有一定的缓释性.     

Preparation and characterization of composite microspheres for brachytherapy and hyperthermia treatment of cancer

Composite microspheres were prepared by coating yttrium-aluminum-silicate (YAS) glass microspheres (20-30 μm) with a layer of Fe₃O₄ nanoparticles and evaluated for potential use in brachytherapy and hyperthermia treatment of cancer. After neutron activation to form the β-emitting ⁹⁰Y radionuclide, the composite microspheres can be injected into a patient to destroy cancerous tumors; at the same time, the composite microspheres can generate heat upon application of a magnetic field to also destroy the tumors. The results showed that the composite microspheres were chemically durable when immersed in a simulated body fluid (SBF), with ~ 0.25% weight loss and ~ 3.2% yttrium dissolved into the SBF after 30 days at 37 °C. The composite microspheres also showed ferromagnetic properties as a result of the Fe₃O₄ coating; when immersed in water at 20 °C (20 mg in 1 mL of water), the application of an alternating magnetic field produced a temperature increase from 20 °C to 38−46 °C depending on the thickness of the Fe₃O₄ coating. The results indicate that these composite microspheres have promising potential in combined brachytherapy and hyperthermia treatment of cancerous tumors.     

Microencapsulation of a hydrophilic drug into a hydrophobic matrix using a salting-out procedure. II. Effects of adsorbents on microsphere properties

Wax microspheres of the hydrophilic drug guaifenesin were prepared by the congealable disperse-phase method using a salting-out procedure. In order to improve the particle properties of the microspheres, adsorbents (colloidal silica, magnesium stearate, and talc) were used during preparation. The effects of adsorbents on microsphere properties such as the angle of repose (AR), compressibility index (CI), geometric mean diameter (GMD), loading efficiency (LE), and in vitro drug release (DR) were determined. The AR, CI, and GMD of the microspheres were significantly reduced in the presence of the adsorbents. Increase in the concentrations of colloidal silica and magnesium stearate led to lower LE and faster DR, while talc showed no effect, which could be due to the particle diameter and specific surface area of the adsorbents. The microspheres prepared with colloidal silica were chosen to be compressed into tablets since they were smaller, more uniform, and had better flow properties than those made with magnesium stearate and talc. The in vitro drug release profile of the microsphere tablets was compared with that of commercially available Mucinex®, sustained release guaifenesin matrix tablets. Similar release profiles were observed between the two tablets. Scanning electronic microscopy (SEM) studies of the broken tablets revealed that the deformation of the microspheres caused by compression was minimal.     

SiO2微球的制备与应用

综述了致密和多孔SiO2微球的制备方法．重点描述了近年来SiO2微球的一些新应用。     

炭微球的结构演变:从实心到中空(英文)

采用简单的空气氧化法由实心炭微球制备中空结构的炭微球。通过场发射扫描电子显微镜、高分辨透射电子显微镜、X-射线衍射仪、拉曼光谱和热重分析仪对产物的形貌和结构进行表征。结果表明:中空炭微球的石墨化程度较低。在炭微球的空气热氧化过程中,反应温度对炭微球从实心到中空的结构演变起着关键性的作用,温度越高,中空炭微球的内径越大、壁越薄。其形成机理可认为是炭微球的曲率和结晶度协同作用的结果。亦即,实心炭微球进行热氧化时,其内部的大曲率和低结晶度更易氧化,以致形成中空炭微球。     

Ni/PS核壳结构纳米复合微球的制备及磁性能

采用乳液聚合法制备了纳米级聚苯乙烯微球,利用化学沉积法在微球表面镀镍,制备出了具有磁性的金属/高分子(Ni/PS)纳米复合微球。利用透射电子显微镜(TEM)、X射线衍射仪(XRD)和能量色散谱仪(EDS)分别对镀镍前后纳米微球的形貌结构、相组成、化学成分进行表征分析,用振动样品磁强计(VSM)测试了不同制备工艺条件下复合微球的磁学性能。结果表明,活化工艺、还原剂浓度、镀液pH值和温度对镀后复合微球的磁性能有显著影响。根据磁性能结果,优化工艺参数,制备了具有规则球形、单分散性好、粒径约为100nm、镀层完整、均匀的磁性Ni/PS核壳结构纳米复合微球,并获得最大的饱和磁化强度Ms=8.8764emu/g。     

磁性高分子微球在核酸分离纯化应用中的研究进展

综述了基于磁性微球的核酸自动提取技术的发展现状,介绍了磁性微球的制备、磁性微球在核酸分离中的应用以及基于磁性微球的分离纯化系统,最后展望了基于磁性微球的核酸自动提取技术的发展前景.     

聚乳酸微球制备工艺的研究

采用O/W乳化-溶剂挥发法,选择聚氧乙烯山梨醇酐单硬脂酸酯(Tween60)为乳化剂,天然高分子明胶作为共表面活性剂,制备出了形态较好的聚乳酸微球,而且在可确定因素固定下来后,在保证成球质量的基础上,可以分别通过调节Tween60和明胶的用量在一定范围内来控制微球的平均粒径。     

Evaluation of Spray-Drying as a Method to Prepare Microparticles for Controlled Drug Release

The possibility to obtain microcapsules or microspheres for controlled release by spray-drying is evaluated. Drugs of different solubilities like theophylline and sodium sulfamethazine, with Eudragit RS as coating polymer, are chosen.

The polymer is used, either dissolved in an hydroalcoholic solution or suspended (pseudolatex) in water, in different weight ratios with the drug. The obtained solution or suspension is spray-dried.

Scanning electron microscope analysis of the powders reveals no sign of microencapsulation. Moreover, only a fraction of the particles has a spherical shape.

For each spray-dried powder, a part of the obtained particles is compressed into tablets, and the rest is stored.

Dissolution studies in distilled water at 37 C are performed on powders and tablets.

While the uncompressed microparticles do not give any controlled release, the tablets show an ability in slowing down drug delivery greater than the one obtained with the traditional methods.