有機共軛自組裝奈米材料在生醫顯像之應用

Abstract

近年來，科學家對分子的掌握日漸成熟，更進一步就是控制分子間的弱作用力，這一門領域便是自組裝材料的起源。本研究以胜肽序列修飾特定pi共軛系統，使系統得到改善或功能。研究主題分成兩個部分進行，各別著重在調控水凝膠流變性質和調控聚集誘導發光的能力。第一部份的萘四羧酸二醯亞胺連接的雙肽能決定水凝膠的強度和成膠環境，比較了C8NDI-FF、C8NDI-FG、C8NDI-GF和C8NDI-GG，發現四者皆能在酸性環境下形成穩定水凝膠，且擁有越多的苯丙胺酸則可以有更強的pi-pi作用力，則能在較接近中性的酸鹼值成膠。在生理環境下，只有C8NDI-FF和C8NDI-FG這兩個凝膠因子能形成穩定水凝膠，此結果證明C8NDI-F這個單元能提供有效的pi-pi作用。研究成果顯示出萘四羧酸二醯亞胺是個適合用於超分子水凝膠的系統。第二部分比較了萘二甲醯亞胺在4號位置連接上不同環數的環烷作為推電子基團時聚集誘導發光的效果，依環烷尺寸小到大分別是5RNI、6RNI、7RNI和8RNI，但只有6RNI表現出聚集誘導發光的特性，雙肽部分則選用苯丙胺酸和酪胺酸的組合，藉由末端雙肽的親疏水性改變就能調控聚集誘導發光的表現，使得在1%二甲基亞碸的水溶液中也能有最佳的聚集誘導發光效果。本研究是第一個利用萘二甲醯亞胺與胜肽產生聚集誘導發光的系統。更進一步還能製備出可發光的奈米和微米不同尺寸的微結構。

In this study, the pi conjugated systems are modified by attaching to peptide sequence to gain some functionality or improvement. This thesis has two different parts. In the first part, we study the rheological properties of peptide hydrogels. Incorporation of a 1, 4, 5, 8-Napthalene tetracarboxylic diimide (NDI) and a dipeptide in the imide position, we found the composition of the peptides can determine the strength and gelation of this type of hydrogels. The four compounds are presented in the study (C8NDI-FF, C8NDI-FG, C8NDI-GF and C8NDI-GG) which forms stable hydrogel in acidic pH conditions. And with the increasing of the number of phenylalanine (Phe), the intermolecular  interactions can be enhanced. When considering the gelators of C8NDI-FF and C8NDI-FG, these hydrogelators can form hydrogels in the physiological environment. These results prove that the presence of the building block of C8NDI-F is an efficient way to construct the supramolecular system. In the second part, we study the properties of aggregation-induced emission (AIE) of the chromophores. The different size of cycloalkanes is used as electron-donating group to modify the 1, 8-naphthalimide (5RNI, 6RNI, 7RNI and 8RNI). Importantly, the 6RNI series exhibit AIE properties. We further extend this study to dipeptides where the combination of 6RNI and phenylalanine (Phe) or Tyrosine (Tyr) is conducted. The difference of hydrophobicity between these two amino acids can alter the properties of AIE. Through this study, we found a simple strategy to fabricate the one-dimensional (1-D) nano- and micro-structures in relatively large scale.