本研究主要探討聚乙二醇-聚酯類雙團聯共聚物(mPEG-PLGA及mPEG-PCLA)之物理、化學性質，在固定親水鏈段與疏水鏈段之分子量比例為550/1405的原則下，調整其疏水鏈段中單體與單體之間的莫耳比例，找出作為溫度敏感型水膠材料之最適化條件。實驗利用開環聚合反應製備出雙團聯共聚物，在mPEG-PLGA系列中依疏水鏈段單體比例不同分為L10、L8G2、L6G4、L4G6、L2G8及G10。而在mPEG-PCLA系列當中，也依單體比例不同分為L10、L8C2、L6C4、L4C6、L2C8及C10。結果顯示，L10、L4G6、L2G8、L2C8、G10、C10因其疏水性或結晶性而不溶於水，其餘共聚物L8G2、L6G4、L8C2、L6C4、L4C6於水溶液中皆可形成奈米微胞，臨界微胞濃度小於0.1mg/ml，粒徑皆在100nm以下。然而mPEG-PLGA系列中15wt%水溶液之成膠溫度為15-50℃，成膠範圍很廣；mPEG-PCLA系列則是降解速度較慢，其中L4C6及L6C4，在降解後之第30天，其重量還有原本的60%以上。其中，L6C4為最適化條件，除細胞毒性測試中，顯示20wt%水膠之良好生物相容性，亦在軟骨修復之動物實驗中，展現其水膠載體優良之特性。縱合上述之研究成果，相信此一mPEG-PCLA系列之共聚合物，適合用於原位注射成膠之藥物釋放系統。

The objective of this study is to discuss the thermo responsiveness properties of methoxy poly(ethylene glycol)-polyesters (mPEG-PLGA, mPEG-PCLA) diblock copolymers. Without changing the hydrophilic/hydrophobic segment ratio of the copolymer, the molar ratio of ester monomers was adjusted to obtain better formulation for a thermal-sensitive hydrogel. Diblock copolymers were synthesized using ring-opening polymerization. For the mPEG-PLGA series, L10, L8G2, L6G4, L4G6, L2G8, and G10 were prepared corresponding to LA/GA ratios of 100/0, 80/20, 60/40, 20/80, and 0/100, respectively. For the mPEG-PCLA series, L10, L8C2,L6C4, L4C6, L2C8, and C10 were prepared corresponding to LA/CL ratios of 100/0, 80/20, 60/40, 20/80, and 0/100 respectively. Results showed that L10, L4G6, L2G8, L2C8, C10 and G10 were insoluble in water due to high crystallinity and hydrophobicity. L8G2, L6G4, L8C2, L6C4, and L4C6 formed nanoparticles with sizes under 100 nm and critical micelle concentrations below 0.1 mg/mL in aqueous solution. Also, it was observed that 15 wt% (w/v) mPEG-PLGA displayed a wide gelation window in water.
Adjusting the molar ratio of monomers in mPEG-PLGA did not significantly alter the gelation window while decreasing the LA units in mPEG-PCLA narrowed the gelation window. In degradation test, mPEG-PCLA series showed slower degradation rate, L4C6 and L6C4 both degraded less than 40% of their original weight after 30 days. In brief, L6C4 hydrogel has optimal ratio, which shows good biocompatibility in cytotoxicity test. Also, L6C4 is a promising drug delivery carrier in cartilage defect regeneration model.
These results demonstrate some diblock copolymers of mPEG-PLGA and mPEG-PCLA can be used as in situ gelling drug delivery systems.

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