本研究合成具聚集誘導螢光(AIE)性質的雙親性嵌段共聚高分子SSPCL-b-P(TEGNA-co-PPSHEMA)及主動標靶(active targeting)性質與數種環境響應性之雙親性嵌段共聚高分子SSPCL-b-P(TEGMA-co-FA)，於水溶液內自組裝形成高分子液胞(polymeric vesicle)，針對其主動標靶功能、環境響應性與螢光性質及此藥物載體對細胞毒性之探討與檢測。
將疏水性鏈段poly(ε-caprolactone)(PCL)作為高分子液胞之雙層膜間之支撐，親水性鏈段PTEGMA作為內外層膜，具有溫度響應性，並在其修飾具癌細胞標靶性質與酸鹼響應性質之葉酸(Folic Acid)，而親疏水鏈端之間存在具有氧化還原響應性之雙硫鍵(disulfide bond)，以形成高分子藥物載體SSPCL-b-P(TEGMA-co-FA)，包覆親水性抗癌藥物阿黴素Doxorubicin。另外，將螢光基團2-(1,2,3,4,5-pentaphenyl-1H-silol
-yloxy) ethyl methacrylate) (PPSHEMA)修飾於相似之雙親性高分子之親水鏈上，以形成SSPCL-b-P(TEGNA-co-PPSHEMA)。
本研究藉由親水外層膜上葉酸基團與HeLa cell上之受器結合，以達到主動標靶功能，促進載體與細胞之接觸，增加胞吞機率，並於癌細胞內部酸性環境下，透過溫度及酸鹼響應性，使載體能在細胞內釋放藥物；透過調整親水鏈段長度，以使最低臨界溶液溫度(lower critical solution temperature, LCST)於中性時高於人體體溫37℃，而酸性時低於37℃，以期此液胞於體循環時穩定，進入癌細胞內則快速釋放；腫瘤細胞之細胞質中，含高濃度之還原劑穀胱甘肽(GSH)，雙硫鍵會因還原斷鍵而造成液胞結構崩解，促進釋藥；螢光基團PPSHEMA與阿黴素之間具光譜的重疊，當兩者距離夠近(<10nm)，會產生Förster Resonance Energy Transfer (FRET)效應，以此判斷藥物包覆程度。
經由藥物釋放實驗結果，可推測此液胞於體循環可將洩漏量減少至約20%，而胞吞進入癌細胞細胞質後，可將包覆藥物幾乎全數釋放；而經由癌細胞與混合液胞共培養之螢光影像結果可得知，此混合液胞可順利經胞吞進入癌細胞，並透過螢光影像得知混合液胞之分布，且可以分析FRET效率值判斷藥物釋放與否，而此混合液胞經細胞毒殺實驗得知IC50約為5 μg/mL。

The purpose of the study was to develop a drug delivery system with multiple functionalities of active targeting, stimuli-responsive, AIE-based fluorescent tracking for potential application in controlled drug release. Towards this goal, we developed a polymeric mixed vesicle system self-assembled from two amphiphilic block copolymers, PCL-SS-b-P(TEGMA-co-PPSHEMA) with aggregation-induced emission (AIE) characteristic and PCL-SS-b-P(TEGMA-co-FA) with active targeting and triple stimuli-responsive features. In this research, we investigated the nanostructure, morphology, stimuli-responsive, fluorescent properties, drug release, and cytotoxicity of HeLa cells of the multifunctional mixed vesicle.
Poly(triethylene glycol methacrylate) (PTEGMA) is the hydrophilic core and shelter of the polymeric vesicle, and Poly(ɛ-caprolactone) (PCL) is the hydrophobic double-layer film of the vesicle, the copolymer of two is amphiphilic, which can self-assemble in the aqueous solution and encapsulate the hydrophilic anticancer drug, doxorubicin (DOX), at the same time. Besides being the hydrophilic chain, TEGMA is also a thermo-responsive monomer, which has a synergistic effect with folic acid (FA), a pH-responsive and active targeting monomer, and thus we polymerized these together by Atom-transfer radical-polymerization (ATRP), the disulfide bond between two chains can also provide the redox-responsive to the product, PCL-SS-b-P(TEGMA-co-FA). Furthermore, we also grafted the fluorescent moieties, 2-(1,2,3,4,5-pentaphenyl-1H-silol-yloxy) ethyl methacrylate) (PPSHEMA), to the hydrophilic chain of another product, PCL-SS-b-P(TEGMA-co-PPSHEMA).
Since HeLa cells are overexpressing folate receptor (FR), folic acid is often applied to the drug delivery system for active tumor targeting to effectively promote cell-specific drug uptake. Due to the pH variation among cellular compartments such as endosomes and lysosomes (pH ≈ 5.3), extracellular tumor tissues (pH ≈ 6.5), and normal tissues (pH 7.4), folic acid can behave its pH-responsive and synergies with TEGMA, keep being stable in blood circulation but collapse after endocytosis.
We adjusted the degree of polymerization of TEGMA and FA, and changed the mixing ratio of PCL-SS-b-P(TEGMA-co-FA) and PCL-SS-b-P(TEGMA-co-PPSHEMA), to control the lower critical solution temperature (LCST), which should be higher than 37℃ in a neutral environment, but lower in an acidic environment, so the vesicle could reach the above goal. Besides, because of the high concentration (10 mM) of glutathione (GSH) in tumor cytosol, the disulfide bond could be cleaved and make the vesicle collapse easier, which is redox-responsive behavior. Förster Resonance Energy Transfer (FRET) would occur when the donor was close enough to the acceptor owing to the spectral overlap of PPSHEMA and DOX. The FRET effect could serve as a basis for monitoring the drug conjugation or release from the vesicles. In addition, in vitro results demonstrated that the mixed vesicles exhibited dose-dependent cytotoxicity to HeLa cells.

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