在本研究中，我們將合成出一系列具有光敏感特性的兩性聚醯胺-乙二胺樹枝狀分 子複合體，除了能夠作為核酸分子的運輸載體，也可以同時進行光誘導控制釋放。我 們在疏水的碳六十或膽固醇分子及親水的聚醯胺-乙二胺樹枝狀分子之間，導入光敏感 的鄰硝基苄基團或香豆素酯基團，並透過自組裝的方式形成核殼型偽樹枝狀高分子； 而透過照光的方式可以讓此自組裝樹枝狀高分子的結構產生降解，進而將加速將所承 載的核酸分子釋放到特定的生物標靶。我們將輔以動態光散射技術、原子力顯微鏡以 及穿透式電子顯微鏡來分析自組裝型樹枝狀高分子聚集體的形貌，以及聚集體與核酸 分子之間的結合行為，並且以膠體電泳法來分析有效基因轉染之最佳化氮磷比與複合 體穩定度。最後我們將藉由綠色螢光蛋白質在特定細胞內的表現或抑制效率，來評估 光敏感兩性載體攜帶長、短鏈核酸分子的能力與基因轉染效率。另外，我們也將初步 探討以碳六十為核心的兩性載體的多功能性，例如作為光動力療法的光敏感劑、活性 氧物質的清除能力等。 In this ongoing research project, we aim to synthesize a series of amphiphilic poly(amido amine) (PAMAM) dendrons with photo-labile building blocks to achieve efficient nucleic acids delivery combined with photo-triggered controlled release. The light-sensitive ortho-nitrobenzyl group (ONB) or coumarin ester will incorporate into the amphiphilic dyads in which the C60 or cholesterol is the hydrophobic core and PAMAM dendrons is the hydrophilic peripheral. Our original idea is that these materials favor a self-assembly process to form “pseudodendrimer” for carrying nucleic acids and that the ONB or coumarin ester allows a rapid structural degradation upon light irradiation. Accordingly, the light-promoted degradation will lead to a controlled release of nucleic acids to specific biological targets. The aggregation behavior of these amphiphilic dyads is going to be investigated by laser light scattering (LLS), atomic force microscopy (AFM), and transmittance electron microscopy (TEM). The gel electrophoresis is adopted for analyzing the stability of the complexes against the enzymatic degradation and for determining the optimized nitrogen-to-phosphorus (N/P) ratios toward effective gene delivery. In vitro gene transfection efficiency by these newly designed materials was evaluated using green fluorescence proteins (GFP) expression or silencing. In addition, a preliminary investigation focused on the multiple functionalities of the C60-based carriers after gene releasing (e.g., triplet photosensitizer for photodynamic therapy or radical sponge for ROS scavenging) will also be carried out in this project.
