基于电纺芯鞘纳米纤维的分子自组装原位协同调控研究

"How far we can push chemical self-assembly" is, without doubt, the most intriguing challenge that waits to be solved in the decades to come. The present project will investigate the synergistic actions of multiple factors on molecular self-assembly for in situ generating functional nanosystems with electrospun core-sheath composite nanofibers as templates. The core-sheath nanofibers consisting of multiple components are fabricated using the "top-down" coaxial electrospinning processes (including triple coaxial electrospinning with organic solvent as outer fluid, coaxial electrospinning with surrounding unspinnable dilute solutions and rising temperature coaxial electrospinning). The building blocks loaded on the filament-forming polymer matrix in the core-sheath nanofibers can be tailored in terms of their component, content and spatial position. The "bottom-up" molecular self-assembly processes can be triggered simply by putting the core-sheath nanofibers into water or aqueous solutions through the dissolution of the filament-forming hydrophilic polymer matrix and the hydrophobic interactions. The core-sheath nanofibers can act as a useful tool to precisely manipulate the transport and contact of the loaded building blocks in a micro-region confined by the nanofibers' diameters, and thus to realize a relatively controllable molecular self-aggregation process. The confinement effect of fibers' diameters on nanoscale, the secondary interactions among the building blocks and between them and the aqueous surroundings, together with the core-sheath structure would act synergistically to push molecular self-assembly to produce the functional nanoparticles. The mechanisms of the core-sheath nanofibers formation using coaxial electrospinning processes and those of the synergistic manipulation effect of selected components, environmental factors and nanofiber structure on molecular self-assembly to generate nanoparticles will be investigated in detail. The successful conduct of the present project will offer new methods for controllable molecular self-assembly of multiple components, give a new avenue for producing man-made self-assembly functional nano materials, develop new functional direction self-assembly systems/technologies and provide a new research platform for achieving interdisciplinary knowledge.

本项目研究以电纺芯鞘纤维为模板、通过多因素协同作用调控分子自组装、构建功能纳米体系。其策略为先通过top-down同轴电纺制备聚合物基芯鞘纳米纤维，再以纤维为模板、利用其直径的纳米尺度限定作用和芯鞘结构的模板作用、在一个微观区域内调控自组装基元分子的转运与接触，实现一个相对可控的bottom-up分子聚集组装过程。研究内容包括：发展同轴电纺工艺（溶剂环流三级同轴纺/稀溶液环流同轴纺/升温同轴纺）；制备新型人工自组装材料即具有成分空间分布特征、多组分复合的水溶性聚合物基芯鞘纤维；通过"溶解-疏水"作用启动分子自组装构建纳米体系；研究芯鞘结构纤维电纺成型机理及其对分子自组装的调控机制；阐明复合纤维组成成分、结构特征和环境因素等对分子聚集组装的原位协同调控机理。项目研究成功将为建立多组分可控自组装提供新方法；为构建新型人工自组装功能纳米材料开发新途径；发展出功能导向的自组装新体系和新技术。

本项目按照资助计划书进行了如下相关研究：1）发展同轴电纺高压静电纺丝技术，制备多组分复合芯鞘结构纳米纤维，以芯鞘纤维为模板、通过多因素协同作用调控分子自组装、构建功能纳米体系；2）发展多种高压静电纺丝工艺，包括溶剂环流二级同轴电纺、传统和改进型三级同轴纺、稀溶液环流同轴纺、升温电纺以及并列电纺工艺，应用这些技术制备多种载药纳米纤维并进行相关表征分析；3）发展多种其它电流体动力学技术，如高压静电喷雾技术、同轴高压静电喷雾技术和溶剂环流型高压静电喷雾技术，应用这些技术，制备多种聚合物基复合载药微纳米颗粒。. 通过对这些内容的研究获得如下重要研究结果：1）多组分复合的水溶性聚合物基芯鞘纤维由于自身即具有特殊的成分空间分布特征、能够通过“溶解-疏水”作用启动分子自组装构建新型功能纳米体系、实现从纤维状结构到颗粒状结构的微观转化；2）以纺丝头的宏观结构为模板，能够通过电纺工艺单步有效地制备出具有复杂结构特征的纳米纤维材料，如三层芯鞘结构、表面薄层空白包裹结构、药物纳米储库、聚合物-卵磷脂芯鞘结构复合材料、以及乔纳斯(Janus)结构等;3)通过各种高压静电喷雾技术的有效实施和调控，成功制备出多种载药微纳米颗粒、赋予颗粒核壳结构、或调控颗粒的外部形状特点；4）应用上述各种方法和电流体动力学技术手段，制备的载有水难溶药物产物在应用上具有良好的目标应用效果，如能够改善难溶药物的溶解性能，促进药物快速溶解；能够调控药物以零级方式均匀释放；能够调控药物以分布多相的方式控制释放；改善药物的透膜吸收性能等。. 项目基于新型微纳米材料的制备与应用，探究了各种微纳材料的制备机理和功能应用机制。项目研究成果能够为为制备功能纳米材料提供新途径、发展出功能导向的新型纳米技术；为材料纳米结构-性质-效用关系的构建提供新策略，为纳米技术、聚合物科学、电流体动力学、药学等相关学科的交叉融合与发展提供研究平台。