基于“DNA/聚合物胶束”纳米线的精确三维网络组装体

Precise self-assembly is an important foundation to realize the functionalization of self-assembly materials, and it is also the top-challenging task to tackle to date in the field of self-assembly. The common methods to realize the precise self-assembly of nanoparticles are controlling the hybridization interactions of DNA oligonucleotides and using DNA origami motifs. However, the sizes of such assemblies are limited by the lengths of DNA oligonucleotides and the sizes of DNA motifs, and it is difficult to prepare large-scale self-assemblies with fine structure. Based on the work of monodisperse core-shell structured nanofibers which are prepared by the electrostatic self-assembly of double-stranded DNA and polymeric micelles, this proposal aims to study the precise self-assembly of end functionalized “DNA/polymeric micelle” nanofibers and guest nanoparticles into three dimensional (3D) network assemblies. We are going to systematically study the effects of length/diameter ratios of nanofibers, end groups of nanofibers and the amount of combined with nanofibers of guest nanoparticles on the 3D network assemblies. It is expected that the scale-up of precise 3D self-assemblies are fabricated with the assist of the “DNA/polymeric micelles”, and this route can be successfully introduced into the area of self-assembly as a general and facile strategy. Furthermore, it will provide new concepts and strategies for the fabrication of macroscopic materials that is assembled by the use of microscopic precise 3D network assemblies.

精确自组装是实现组装材料功能化的重要途径，也是当今自组装领域的难题之一。其中利用单链DNA的碱基互补配对和DNA折纸术是实现纳米粒子精确自组装常用的策略。然而由于所用DNA的长度有限，导致获得的组装体尺寸较小且难以形成具有精确结构的大尺度功能材料。本申请基于双链DNA与聚合物胶束通过静电作用得到单分散纳米线的工作，拟利用端基官能化的“DNA/聚合物胶束”纳米线与客体纳米粒子的特异性相互作用实现精确自组装并得到三维网络组装体。通过调节纳米线长径比，客体纳米粒子结合纳米线的多寡以及纳米线端基种类等方式，获得具有不同间距、形状各异和多种纳米粒子交替的三维网络组装体。期望通过深入研究，能够实现基于“DNA/聚合物胶束”纳米线的精确自组装，获得更加稳定的大尺寸三维网络组装体。并将该路线作为一种通用的精确自组装方法引入到自组装材料研究领域，为宏观自组装材料制备提供参考。

精确自组装是实现组装体功能化的重要途径之一，但目前人为精确操控自组装依然十分困难。在国家自然基金青年项目的支持下，我们计划利用末端功能化的“DNA/聚合物胶束”纳米线与金属纳米粒子作用实现有机-无机杂化材料的三维精确自组装。在研究过程中我们发现纳米线的自组装行为受到胶束稳定性、纳米线结构及外界环境等多种因素的影响。虽然已尽全力优化实验条件，但最终仍未能成功获得具有三维精确结构的组装体。为了解决三维精确自组装过程中碰到的问题，我们开展了部分针对性的研究。我们利用DNA可精确修饰、可快速合成的特点，通过不同策略实现了无机-有机杂化纳米线一维结构的精确组装及快速制备。以上研究对后续开展纳米线的二维及三维精确组装有一定的参考价值。我们也通过单分子力谱对嵌段共聚物单链力学行为及胶束结构的稳定性进行了研究，获得了嵌段共聚物在不同环境中的单链行为与聚合度的关系、嵌段共聚物胶束在水环境中稳定性的定量结果以及外界环境对胶束稳定性的影响。通过研究嵌段共聚物单链及胶束在不同环境中的行为，可以帮助我们在后续自组装研究过程中有效调控聚合物胶束及纳米线的构象及行为，促进三维精确组装体的构筑。此外，我们还评述了近20年来高分子单链行为受外界环境影响的单分子力谱研究。

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