本研究將聚乙二醇(poly(ethylene glycol), PEG)兩端共聚合上丙胺酸(ʟ-alanine)，形成一三嵌段共聚物PA-PEG-PA(PEA)，希望藉由改變材料親疏水性質，來促進細胞與材料之間的貼附，再經由末端烯基化改質，將其末端接上丙烯醯基(acryloyl group)，使其成為具有光交聯性質之兩性高分子PEA-DA，經過末端烯基化改質後，即可利用紫外光(UV light)對此材料進行照射，藉此引發光聚合反應，形成光交聯水膠，進一步增強其機械性質。
將不同濃度之水膠進行膠含率、含水率、結構型態與機械性質之量測，實驗結果發現濃度10 wt%之水膠具有較佳的成膠性質及機械強度。由水膠毒性測試之結果，可以發現將水膠先浸泡於培養基的方式能有效的溶出殘留在膠體中的光起始劑，降低對細胞的毒性，其細胞存活率皆維持在90%以上。隨後進行細胞與水膠共培養之測試，觀察細胞存活率及在膠體中之生長情形，由MTT assay結果可看出第七天之細胞存活率皆高於第四天，證明細胞可在此膠體環境下作生長，而由Live/Dead assay結果發現細胞會鑽進PEA-DA水膠內作生長，而非貼附於水膠之表面。接著以定量逆轉錄聚合酶鏈式反應及免疫螢光染色進行人類臍靜脈內皮細胞(HUVECs)之功能性測試，其結果發現，在共培養七天後，PEA-DA水膠組別之特定基因表現量皆高於PEG-DA水膠組別，證明共聚合上Alanine之PEA-DA水膠，雖然在細胞存活率的改善方面幫助不大，但在長期的培養下，相較於PEG-DA水膠，可以讓人類臍靜脈內皮細胞有更高的表現量。

In this study, ʟ-alanine were copolymerized at both ends of poly(ethylene glycol) forming a triblock copolymer PA-PEG-PA(PEA) to promote cell adhesion. Then the terminal group of PEA were modified by acryloyl group to make it an amphiphilic block copolymer with photo-crosslinking property. After modification of terminal group, the material can be exposed to ultraviolet light (UV light) to induce photo-polymerization, and obtain photocrosslinked hydrogels which have greater mechanical strength.
We observe and measure the gel fraction, water content, structure and mechanical property of hydrogels in different concentration. The results showed that hydrogels with concentration of 10 wt% had better gelation property and mechanical strength. According to the results of hydrogel toxicity test, soaking the hydrogel in the medium can effectively remove the unreacted polymer and the remained photoinitiator to reduce the toxicity of hydrogel. The cell viability all maintained at more than 90%. Subsequently, cells and hydrogels were co-cultured to observe cell viability and the growth in the hydrogel. According to the results of MTT assay, the cell survival rate of the seventh day was higher than the fourth day, demonstrating that the cells can grow in this environment very well. However, Live/Dead assay results showed that cells migrated into PEA-DA hydrogel instead of attaching to the surface of the hydrogel. Functional characterization of human umbilical vein endothelial cells (HUVECs) was performed by quantitative reverse transcriptase polymerase chain reaction and immunofluorescence staining afterwards. As a result, it was found that the specific gene expression of the PEA-DA hydrogel group was higher than the PEG-DA hydrogel group after seven days of co-culture, demonstrating that the PEA-DA hydrogel which copolymerized with Alanine does not help much in improving the cell survival rate, but the human umbilical vein endothelial cells express higher specific gene expression compared with PEG-DA hydrogel in the long-term cultivation.

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