功能性自組裝體的制備研究

摘 要：新型組裝基元的構筑和組裝體的功能是自組裝研究的兩個核心問題。該研究分別在這兩個方面取得了一些進展。各向異性組裝基元的出現極大地豐富了自組裝的研究內容，并為制備高度有序和復雜的組裝體提供了新工具，但目前已報道的各向異性組裝基元一般限于微觀和亞微觀尺寸。該研究制備了分子水平的各向異性粒子，并發現其具有獨特的自組裝行為。比如：合成了分別具有一個環糊精基團和一個偶氮苯基團的超支化聚合物，然后通過環糊精和偶氮苯之間的主客體復合，偶聯得到了Janus型超支化聚合物，且該各向異性聚合物可以進一步自組裝形成均一的納米囊泡，而且所制備的囊泡可以進一步組裝形成類似膠子晶體的多級結構。這種高度均一的囊泡組裝體是十分罕見的。該課題還在組裝體的功能化方面開展研究。例如：長期以來仿細胞模型體系一般只限于對細胞膜結構的仿生，但實際上細胞在發生結構轉變時往往伴隨著功能的表達。最近，我們制備了具有pH響應的聚合物囊泡，該囊泡可以在pH觸發下實現可逆的收縮和膨脹，最為重要的是在這個形變過程中，同時伴隨著囊泡熒光的增強和淬滅。整個過程和綠色熒光水母的呼吸過程有些相似。這是目前已報道的為數不多的結構和功能同時表達的一個人工模型膜體系。

關鍵詞：自組裝 各向異性粒子 超支化聚合物 囊泡 細胞模擬

Abstract： It is centrally important for self-assembly research to construct new building blocks and attain new functionalities. We made some progress in these two topics in 2013. Anisotropic particles are new building blocks for self-assembly， which greatly enrich the scope of self-assembly and provide a new toolbox to construct highly ordered and complex self-assemblies. However， most of the reported anisotropic particles are limited in microscopic or submicroscopic scale. Recently， we have extended it into the molecular level， and found new self-assembly behaviors can be realized from these building blocks. For instance， we constructed a Janus hyperbranched polymer by the noncovalent coupling between a hydrophobic hyperbranched poly（3-ethyl-3-oxetanemethanol） with an apex of an azobenzene （AZO）group and a hydrophilic hyperbranched polyglycerol with an apex of a β-cyclodextrin （CD） group through the specific AZO/CD host？guest interactions. This amphiphilic supramolecular polymer can further self-assemble into unilamellar bilayer vesicles with narrow size distribution， which could further aggregate into colloidal crystal-like close-packed arrays under freeze-drying conditions. Such a well-defined and uniform vesicle structure has seldom been observed. Besides， we also focused on the functionalities of self-assemblies. For example， in cytomimetic chemistry， most of the works are concentrated on the structure mimics of cells but seldom involve the functionalities therein. Recently， we produced a pH-responsive polymer vesicle through the aqueous self-assembly of an amphiphilic diblock copolymer consisting of many fluorescent chromophores of dimethylaminoazobenzene. They exhibited pH-responsive breathing behavior involving the swelling and shrinkage of the vesicles. Furthermore， in analogy with jellyfish， the fluorescence is quenched when the vesicles breathe in， whereas a strong green fluorescence is emitted when the vesicles breathe out. Such a cytomimetic behavior in combination with the structure and functionality express has seldom been observed before.

Key Words： Self-assembly； Anisotropic particles； Hyperbranched polymers； Vesicles； Cytomimetic chemistry

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