【作者】 张琦；

【导师】 常津； 王建平；

【作者基本信息】 天津大学 ， 材料学， 2010， 博士

【摘要】 在单分散功能化聚合物微球研究中存在着微球粒径均匀性不高、分离纯化困难、功能化后难以满足使用要求等问题,限制了其在生物医学领域的应用。为获得粒径更为均匀的聚苯乙烯微球,本文通过分散聚合和种子聚合制备了粒径为1~10μm的单分散微球,采用苯乙烯和含官能团单体共聚合成了表面官能化微球;推导了一个基于理想单体吸收过程的模型,并检测了实验过程中微球粒径的变化,同时详细分析了初始颗粒与最终微球之间粒径和变异系数的比率变化趋势。比较理论分析结果和实测数据可知,更均匀的初始种子颗粒和精细调节实验参数可制得更均匀的微球。研究了单分散聚合物微球在溶液中的运动,通过理论推导发现微球的运动时间(即上浮时间或沉降时间)正比于溶液的粘度,反比于微球与溶液之间的密度差和微球半径的平方。本方法依据微球在甘油水溶液中的运动时间,可简便测得毫克级单分散微球的表观密度,与供应商提供值相比,该测量值可更精确地预测微球在溶液中运动情况。此外,采用该方法能有效地分离纯化聚合后所得微球混合物,所推导的效率公式可用于优化分离过程。将Fe3O4纳米颗粒偶联于空白聚合物微球表面,制得磁性纳米颗粒杂化聚合物微球;使用改良的梯度选择法,从反应后的混合液中分离磁性聚合物微球。结果表明,当混合液分散在50 wt%甘油水溶液中时,密度低于溶液的杂化微球上浮,密度高于溶液的纳米颗粒沉降,由于二者在溶液中运动方向相反,微球迅速被分离纯化。经本法纯化的微球表面未除去的纳米颗粒比传统离心法和外部磁场法低35~55 %左右。采用溶剂逐渐挥发法,在微球染色过程中形成荧光素(即罗丹明101和吖啶橙)的高浓度溶液,制备了高亮荧光微球。结果表明,制备的微球荧光发射光谱宽,可发出黄、绿、红、猩红等各种颜色的荧光;与市售荧光微球相比,单球荧光强度相对值高约10~50 %。综上所述,本研究在细胞分离纯化、疾病早期诊断等领域中具有潜在的应用价值,为其提供了重要的理论支持和实验依据。更多还原

【Abstract】 The development of multifunctional monodisperse polymer microspheres has been hampered by several problems, such as inhomogeneous size distribution, a lack of efficient purification methodology, weak performance in the application of biomedicine.Herein, we fabricate the monodisperse polystyrene microspheres via dispersion polymerization and seeded polymerization with a diameter range from 1 to 10μm. The functionalized microspheres were obtained by co-polymerization of styrene and co-monomers with functional groups. To clarify the size distribution relationship between the final fabricated beads (by seeded polymerization) and the initial seed particles (by dispersion polymerization), a theoretically investigation according to the principle of the ideal monomer absorption process was employed. And the size growth process was experimentally measured. In the meanwhile, the diameter and coefficient variation rates of the final fabricated beads to the initial seed particles were also investigated. Compared the measured size distribution with the estimated, it was found that the more homogeneous beads can be generated by selection of more uniform initial seed particles and meticulous adjusting synthesis parameters.A new, facile and milligram-scale method was developed to describe the motion of polymer beads in aqueous solution. The motion time (i.e. floating or sedimentation time) of beads in solutions is proportional to the viscosity of solutions. It is reverse proportional to the square of bead radius and the density difference between the beads and the solutions. The apparent density of monodisperse beads can be quickly and easily calculated using the motion time of polymer beads in glycerol aqueous solutions. The results indicated that the present method provided a more precise way to predict the movement of beads in aqueous solution compared with the approach for commercial use. Moreover, this method was developed to purify polymer beads from the reaction mixture containing larger beads, target beads and smaller second-nuclei beads. The efficacy equation was derived to predict the purification process.The magnetic nanoparticle-polymer hybrid microbeads were prepared by coupling blank polymer beads with magnetic Fe3O4 nanoparticles. A facile method, density selection method was introduced to isolate magnetic polymer beads from unattached nanoparticles based on their density difference. As the mixture of bead and nanoparticle was dispersed in 50 wt% glycerol solution, the lighter bead would float to the upper surface of medium, and the heavier nanoparticle had a tendency to settle towards the bottom of container. The bead could be efficiently collected due to the bead movement direction opposite to that of nanoparticles. The amounts of unremoved MNPs of purified beads were 35~55 % lower than those of beads by general centrifugation or external magnetic field separation methods.The fluorescent polystyrene beads were stained by gradual solvent evaporation method using dyes such as rhodamine 101 and acridine orange. Gradual solvent evaporation method facilitates a high concentration of fluorescent dyes on beads. This is the key to obtain fluorescent beads with high intensity. The results showed that the fabricated fluorescent microspheres could be excited to various wavelengths (such as yellow, green, red and scarlet). Our synthesized microspheres offer high fluorescence emission intensity compared to commercial fluorescent microspheres in the mean time have other properties in common.This study can be potentially employed in cell separation, microfluidics chip systems, early disease diagnosis, flow cytometry, suspension stability, and particle analysis systems.更多还原