本實驗室先前所研發的生醫動態光罩快速成型系統製作PLGA混合PEG-HEMA支架，製作過程中，支架持續浸泡於有機溶劑溶液中，易造成未交聯的材料產生二次溶解。故本研究針對材料進行改質，以改善交聯情況，解決此問題；並對交聯後的材料進行降解測試與體外細胞培養，了解改質後之性質與差異。
首先將PLGA材料進行末端OH鍵結改質為acrylate group C=C雙鍵，此雙鍵可受光激發交聯產生化學鍵結；因PLGA相對於acrylate group分子量過大，易造成鑑定上之困難，故又自行合成分子量較小且具有類似結構的PCL-PEG-PCL生醫材料，並加以改質，輔助驗證PLGA的改質成功與否。改質後的生醫材料，透過核磁共振儀與紅外線光譜儀，證明其末端改質為C=C雙鍵的成功性；其抗拉強度亦有明顯提升，顯示材料改質後，具交聯結構，而非原先之半滲透網狀結構。此外，將製作好的薄膜支架浸泡於氯仿溶液，進行重量損失量測，評估材料改質對二次溶解改善效果，得知二次溶解與acrylate group的接枝率有密切關係。降解測試，包括含水率量測、酸鹼值量測及重量損失率量測。因生醫材料改質會破壞原有的結晶性，而使其降解速率略為加快。細胞體外培養採用L929纖維母細胞與MG63類骨母細胞，並經由生物毒性反應測試、電子顯微鏡及倒立式顯微鏡等，檢測細胞生長於支架上的形態及活性。
本研究成功將PLGA及PCL-PEG-PCL兩種生醫材料末段改質為C=C雙鍵，交聯後成功地改善二次溶解問題。改質後的生醫材料，降解速率略增，但其非生醫材料的acrylate group並不影響細胞生長。

In the previous Dynamic Mask Rapid Prototyping System developed in our laboratory, PLGA was mixed with PEG-HEMA to create scaffolds. During the fabrication, the finished scaffold layers continue to be soaked in the organic solvent, resulting in re-dissolution of the non-photo-crosslinked material (or called semi-interpenetrating networks, semi-IPNs). In order to solve this problem, biodegradable materials were modified to improve crosslink in this research. Moreover, degradation tests and in vitro cell culture were performed to understand properties and differences of the modified materials.
In the material modification, the OH bond of PLGA end was replaced by the C=C bond of the acrylate group, which can be photo-initiated to crosslink. Due to the large differences in molecular weight between PLGA and acrylate group, it may cause problems in verifying the acrylate replacement. Therefore, PCL-PEG-PCL with less molecular weight but similar structure to PLGA was also synthesized and replaced by acrylate group to assist the verification of the material modification. Both modified materials were successfully examined by the Nuclear Magnetic Resonance and the Infrared Rays Spectroscopy. The tensile strength of cured materials were obviously increased to demonstrate the crosslink networks exist instead of semi-IPNs. In addition, in order to prove the re-dissolution problem has been solved, the cured thin films of the modified materials were soaked in the chloroform solution and measured the weight loss. The results showed that the improvement of re-dissolution problem was closely related to the acrylate group grafting ratio. Degeneration test included water absorption ratio, pH value test, and weight loss ratio. Because the replacement of acrylate groups partially destroyed the original crystalline structure, the modified materials showed slightly faster degradation. L929 fibroblast cells and MG63 human osteoblast-like cells were cultured on porous scaffolds in vitro for three days. The cell growth morphology was observed by optical microscope and SEM, and evaluated by MTT assay kits.
This research successfully modified biodegradable PLGA and PCL-PEG-PCL materials and improved the re-dissolution problem. The modified materials degraded slightly faster, but the non-biodegradable acrylate group did not affect cell growth.

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