超分子奈米結構之聚集誘導發光特性及酸鹼度感測器之應用

Abstract

本論文研究方向為探討一系列低分子量超分子自組裝奈米結構，研究主軸為探討其聚集方式誘導螢光特性及對酸鹼度敏感的感測器。在第一部分中設計全氟苯二肽分子，固定全氟苯及苯丙胺酸的順序，調控系統中第一個胺基酸側鏈的疏水程度，在不同水比例的螢光光譜中，可觀察到PFB-IF在富含水的溶液中螢光強度相比於純二甲基亞碸中增加約200倍。在此系統中，僅使用單一六環共軛結構配合胜肽序列所產生的聚集誘導發光現象 (AIE)，可使放光區移至可見光區，其作用力為側鏈基團的空間立體阻礙、全氟苯二肽結構中的疏水作用及全氟苯和苯丙胺酸中的苯基間的四極矩-四極矩相互作用力所表現出的J型聚集體，其為目前具AIE效應之水凝膠中分子量最小者。在奈米結構調控中發現PFB-LF可利用溫度和濃度調控出胜肽型奈米粒子，同樣的條件下PFB-IF沒有觀測到此現象，仍為奈米纖維的形貌，比較兩者結構僅改變一個胺基酸且其為同分異構物 (Ile為異白胺酸和Leu為白胺酸)，後續將深入研究白胺酸在奈米粒子中扮演的角色且降低氟原子效應，使平均粒徑介於150-200 nm之間，應用至藥物釋放系統中。 第二部份中，我們將萘二甲醯亞胺及其衍生物與功能性胜肽序列結合，保留螢光團特性的同時也兼顧其生物相容性，測試不同的酸鹼值的螢光特性，皆觀測到酸性條件下螢光急遽增強的現象，具有溶酶體細胞顯像的潛力，測試其細胞顯像，將化合物與商用Lysotracker Red DND-99共同染色2小時，可知ppNI-FDGEA與商用Lysotracker Red DND-99的螢光面積之共定位係數達84.14 ± 2.99 %重疊率，可應用至細胞內之溶酶體綠色螢光探針。因DGEA胜肽序列對 alpha2beta1 受器具有專一性，進一步比較不同的細胞株PC-3 (DGEA positive) 和 22Rv1 (DGEA negative)，因PC-3細胞表面具有 alpha2beta1受器，ppNI-FDGEA容易進入細胞，細胞內化合物濃度提高，可得到較好的染色效能。而螢光團多為疏水性，而使用之DGEA胜肽序列具親水性，故我們測試其成膠能力，發現此系列化合物皆可形成水凝膠，且具有高生物相容性，後續可將本研究中之萘二甲醯亞胺(NI) 及其衍生物 (ppNI) 可結合其他細胞外基質中特定蛋白的衍生物序列，應用至三維細胞培養中。

In this study, we have synthesized a series of peptide-based low molecular weight hydrogelators. This thesis has two-fold part. In the first part, a new class of organic hydrogelators are developed. These three-dimensional hydrogels contain nanofibrous structures with average widths of ca. 10-12 nm, which prepared via self-assembly of small molecules (PFB-dipeptides) in water. The PFB-dipeptide is weakly fluorescent in solution, but the intensity is increased by almost ~200-fold in the assemblies. The aggregation-induced emission (AIE) in the PFB-dipeptide nanostructures is unusual because there is no AIE-capped moiety in the molecule. The origin of the unusual AIE character is attributed to the side chain steric and hydrophobic effects of amino acids in the structure of PFB-dipeptides and the presence of intermolecular J-type quadruple-quadruple interactions of perfluoropheny-phenyl pairs between the PFB-dipeptides in the assemblies. This work illustrates the importance of the structure-property relationship on the development of new nanoscience and self-assembly nanomaterials. In the second part, a new series of self-assembled peptide nanostructures based on naphthalimide were synthesized and studied, the materials have significant differences in their fluorescence intensity, which have a higher emission peak at acidic conditions. Cell imaging was observed small spherical organelles (lysosomes) in live human prostate cancer PC-3 cell line and significant colocalizations (84.14 ± 2.99 %) of the sensor ppNI-FDGEA with a commercial available Lysotracker Red DND-99 probe by confocal fluorescence microscopy. This design template may also be used to synthesize other functional peptide sequences with potential applications in tissue engineering.