【作者】 亢海刚；

【导师】 朱以华；

【作者基本信息】 华东理工大学 ， 材料科学与工程， 2010， 博士

【摘要】 聚合物纳米纤维具有较高的比表面积、良好的机械性能,在药物传输和靶向释放、组织工程、植入物表面改性等方面都有广泛的应用。静电纺丝技术是制备纳米级连续纤维的唯一方法,设备简单、操作容易,是构建合成及天然高分子聚合物、聚合物合金、含生色团聚合物以及金属陶瓷等纳米纤维的最有效的方法,也是制备纳米颗粒及生物活性物质等功能化纳米纤维的新型手段。将静电纺丝纳米纤维作为载体材料,采用不同的修饰方法,可以得到具有特定应用目的的、结构多样、性能优异的复合纳米纤维,在光电器件、传感技术、催化、过滤、生物以及医用领域都有诱人的应用潜力。本课题围绕静电纺丝纳米纤维高长径比、高比表面积、形貌可调和易于功能化等方面的优点,采用静电纺丝技术制备了介孔二氧化硅纳米纤维,并将其作为载体材料实现与纳米粒子及生物高分子的有效复合,得到一系列性能优异、电化学活性优良、生物相容性良好的复合纳米纤维,最后对其应用价值进行了初步研究。主要完成了以下几个方面的工作：(1)将溶胶—凝胶法与静电纺丝技术相结合,以PVP为赋形剂、P123为结构导向剂,制备了介孔二氧化硅纳米纤维。考查了溶胶pH值、硅水比、PVP种类、陈化温度和时间、搅拌时间及PVP加料时间对电纺过程的影响。探讨了溶剂蒸发诱导自组装法(EISA)对模板剂有序组装的影响,优化了纤维形貌的控制因素。实验结果表明：在纺丝电压为10 kV、纺丝距离为20 cm的纺丝条件下有利于得到直径均匀、单分散性良好的纳米介孔二氧化硅纤维；所制备的纤维具有双分布的介孔结构,大部分介孔尺寸为3.70nm,部分约为13 nm。小的介孔基本沿纤维轴向分布而大的介孔则自由分布。纤维具有极高的比表面积和孔容,分别为2988.70 m2／g和4.40 cm3／g。通过改变后处理工艺,将电纺纤维经过水蒸气老化处理和H2O2氧化降解模板剂P123后制备了形貌保持完好、具有均匀介孔的二氧化硅支撑的PVP纤维,纤维直径约700 nm,介孔平均孔径14.98 nm,孔容0.12 cm3／g,比表面积32.07 m2／g。(2)在纺丝溶胶的配方中原位掺杂硝酸银,利用硝酸银的热解还原机理和PVP的还原保护机理制备了银掺杂量不同的介孔二氧化硅复合纤维带。结果表明,复合纤维带具有独特的带状形貌,宽高比较大,厚度较薄,表面光滑,纳米银粒子分布均匀,平均直径约为31.50 nm。独特的形貌结构使复合纤维带对亚甲基蓝溶液的硼氢化钠还原反应具有很高的催化活性。以此纤维为固定化载体,负载葡萄糖氧化酶(GOx)和细胞色素C(CytC)后构筑了生物传感器,电化学实验表明复合材料具有较好的直接电子传递作用。(3)采用静电自组装方法在二氧化硅纤维表面修饰了一层粒径和分布密度可控的纳米金粒子,并以此修饰纤维为生长核分别在HAuCl4的PVP溶液和K2CO3的HAuCl4溶液中还原生长,最终得到具有完整金壳的SiO2@Au核壳复合纤维。考查了不同制备方法、操作工艺和R值(PVP中乙烯吡咯烷酮结构单元与HAuCl4的摩尔比)对纤维结构和形貌的影响,并以此复合纤维作为电子传输介质构筑葡萄糖氧化酶(GOx)生物传感器。研究结果显示,较低的R容易产生较厚的金壳,较高的R值有利于得到厚度较薄且均匀的致密的金壳。电化学实验表明生物传感器具有优良的电化学特性和灵敏的响应性,在C-V曲线出现了对称清晰的氧化还原峰,峰电流超过0.10 mA,证明此核壳复合纤维可充当电子媒介体在生物杂化系统中得到广泛应用。更多还原

【Abstract】 Nano-scale polymer fibers have high surface volume ration and excellent mechanical property, so they can be exploited for the applications of drug delivery or target release, tissue engineering, surface modification of insert and so on. Electrospinning is currently the only versatile method of fabricating continuous fibers with diameters down to a few nanometers. The method can be applied to synthetic and natural polymers, polymer alloys, and polymers loaded with chromophores, nanoparticles, or active agents, as well as to metals and ceramics. If the electrospun fibers were used as carrier matrix and chemically modified, they can be endowed with different functions, various nano-structures, tailorable morphology and excellent property, which can be applied to the fields as diverse as optoelectronics, sensor technology, catalysis, filtration, and medicine or medical care. This dissertation paid attention to the advantages of high aspect ratio, high surface volume ration, talorable morphology and easy functionalization ascribed to electrospun fibers, and synthesized mesoporous silica nanofibers via electrospinning. These fibers were then used as template and followed by chemical modification so as to combine with nano particles or biomolecules, which showed excellent electrochemical activity and biocompatibility. Main completed researches are shown as follows:(1) Mesoporous silica nanofibers were synthesized by a facile combination of electrospinning technique and sol-gel method. Tetraethyl orthosilicate, polyvinylpyrrolidone (PVP), triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer Pluronic P123 were the components of sol for the production of silica fibers. Heat removal of structure-directing agent P123 and excipient PVP in the hybrid fibers at high temperatures resulted in mesoporous morphology. The effect of pH value, silica water ratio, PVP molecular weight, aging temperature and time, stirring and time point of PVP addition on electrospining precess were investigated. Simultaneously, the effect of evaporation induced self-assembly (EISA) on the ordered assemble of P123 template was also investigated, and the influencing parameters on electrospinning were optimized. Experiments showed that silica fibers with uniform size and integrated morphology were prepared on the optimal electrospun conditions of 10 kV driving voltage and 20 cm receiving distance. The silical fibers have bimodal size distribution, and the average pore diameter, surface area and pore volume are 3.70 nm,2988.70 m2/g and 4.40 cm3/g respectively. Changing post treatment process, after the as-electrospun fibers were aged in hot vapor and extracted in H2O2 the silica-sustained PVP hybrid fibers were successfully synthesized. These fibers have narrow pore size distribution, and the average pore diameter, surface area and pore volume are 14.98 nm,32.07 m2/g and 0.12 cm3/g respectively.(2) Novel silver nanoparticles doped silica fibers with ribbon morphology were synthesized by in situ adding silver nitrate to electrospun sol followed by thermal decomposition of siver and protective reducing mechanism of PVP. The composite nanoribbons present the width of approximately 10μm The content and size of silver nanoparticles encapsulated in ribbons can be readily controlled by varying the concentration of silver nitrate and thermal treatment conditions. Average size of silver particles is 31.50 nm. The silver nanoparticles in the ribbons exhibit good catalytic activity on the reduction of methylene blue dye with NaBH4 as a reducing agent, which is given by the ultra-high surface of the ribbons and their very small thickness. After loading glucose oxidase (GOx) and cytochrome C (Cyt C), the Ag-doped silica ribbons were used to fabricate GOx and Cyt C amperometric biosensors. Electrochemical results show that the hybrid ribbons facilitate electron transfer from active center of enzyme to electrode surface.(3) Mesoporous silica fibers were used as templates for the modification of gold nanoparticles via layer by layer self-assemble method (LbL), and then the gold-seeded silica fibers were further coated by continuous and uniform gold shells via solution-phase reduction of an appropriate metal ion in PVP or K2CO3 solution. The thickness and morphology of gold shell could be tailored by the molar ration of repeating units of PVP to gold ions (R), operation process and growth time. Experimental results show that the low R tend to form the thick gold layer with sharp tips, whereas high R favor obtaining the thin and uniform Au shell. The SiO2@Au fiber hybrid nanostructures are further used as substrates for fabrication of GOx biosensor, which exhibites excellent bio-electrochemical activity with high sensitivity and rapid response. These hybrid nanostructures are, therefore, regarded as molecule wires for potential application in highly sensitive chemical or biological sensors.更多还原