- 學位論文
陽離子型團聯式共聚物與DNA錯合之階層性自組裝行為研究
Study on Hierarchical Self-assembled Structure of Cationic Block Copolymer/DNA complexes
摘要
本研究探討陽離子型團聯式共聚物PS-b-P4VP(CH3I)與生物高分子電解質DNA錯合的自我組裝結構。在水中所形成的錯合物，由於PS鏈段的疏水性，使其奈米結構缺少長程規則性；然而，在THF/H2O共溶劑中形成之錯合物呈現一高度規則性層狀結構，此結構由非極性的PS層與極性的P4VP(CH3I)/DNA層所堆積而成，此外，我們亦發現DNA分子在P4VP(CH3I)/DNA親水層中有規則排列，故在THF/H2O共溶劑中PS-b-P4VP(CH3I)與DNA形成了階層性結構的錯合物。利用電子密度圖譜的分析，我們進一步建構錯合物內部的奈米結構。除此之外，藉由再水合錯合物與cross sectional area分析等研究，我們針對極性層中DNA與P4VP(CH3I)鏈段的鍵結行為進行更深入的解釋。
並列摘要
In this study, we investigated the self-assembled structures of a cationic diblock copolymer PS-b-P4VP(CH3I) complexed with DNA. The nanostructure of the complex prepared in H2O is nanostructure lacked obvious long-range order due to poor solvent for PS chain. However, SAXS profiles and TEM images of the complex prepared using H2O/THF mixed solvent revealed the formation of a long-range ordered lamellar structure with the interlamellar distance of 32nm. In this case, the complexation with DNA induced a structural transition of the copolymer domains from P4VP(CH3I) cylinder to lamellae. In addition to this structural order at the length scale of tens of nm, a smaller-scale structure characterized by the length scale of 2.56nm was found due to the ordered packing of DNA within the polar layers. Using the electronic density profile analysis, a model for the internal nanostructure of the complexes was proposed. The self-assembled structure is governed by the electrostatic interaction between P4VP(CH3+) block and DNA as well the conformational entropy of the PS block covalently linked with P4VP(CH3+) block.