目前治療軟骨損傷方式的成效不甚理想，臨床上面臨的問題有新生軟骨為纖維軟骨，與原有透明軟相比，其機械性質和功能有異；自體軟骨細胞移植有癒後不佳、細胞不易滯留等狀況。近年組織工程不斷發展，研究生醫材料結合幹細胞、軟骨細胞的方式，應用於軟骨修復，有望提高軟骨組織再生能力及完全修復的可能性。在材料選擇方面，水膠提供許多優點作為軟骨修復，如高吸水性可提高良好養分傳輸率、良好的包覆特性，將細胞、藥物、生長因子傳遞至受損處進行修復。雖然許多研究顯示水膠擁有不錯的修復效果，但仍有問題待解決，如機械性質不佳、生物相容性低等，這些狀況不利作為良好的軟骨修復支架。因此本研究探討開發新型生物相容性佳且具雙重交聯水膠為目的，水膠成型透過溫感與光固方式聚合，此雙重聚合不但可以提升水膠機械性質，還能保有各自優點應用在水膠上，提供良好的環境供細胞生長。
本研究成功開發具有生物相容性佳殼聚糖為基底的雙重交聯水膠，從化學結構分析中，可得知成功鍵結光交聯甲基丙烯酸酐官能基與溫感性質的異丙基丙烯醯胺。在實驗組別中分成不同濃度2%與5%的雙重交聯與單一濃度2%光固化型水膠，從SEM結果可以觀察到雙重交聯水膠具有良好孔洞成型，在流變檢測、壓縮力學實驗中可以得知雙重交聯水膠與單一光固化水膠相比，機械性質大幅提升；膨潤、降解實驗中，雙重交聯水膠有良好的養分傳輸率與穩定降解速率；生物相容性結果、螢光染色分析中，雙重交聯水膠為無毒性，同時利於軟骨細胞在其穩定生長。
其中5%雙重交聯水膠表現結果優於其他組別，具有快速成膠、良好孔洞性、較佳的機械性質、良好細胞貼附、不具細胞毒性等優點。在流變學分析中，儲能模量與濃度、材料交聯有正向關係，5%雙重交聯水膠的儲能模量與其他組別相比至少高於10倍。在機械壓縮性質驗證中，5%雙重交聯水膠的壓縮模數可達到109 kPa，與單一光固型組別相比提高3.5倍，再次證實雙重交聯方式可以提升水膠機械性質。細胞貼附實驗，可以觀察到軟骨細胞穩定的貼附生長在5%雙重水膠上；螢光染色中，可以觀察到軟骨細胞穩定的生長於水膠中，細胞型態沒有改變;生活相容性實驗，細胞表現極佳的存活率，且維持穩定生長。在生化分析、組織染色方面上，5%雙重交聯水膠可觀察到少量的基質分泌，其結果優於其他組別。
此雙重交聯水膠有望作為新穎的軟骨修復材料，未來可配合臨床關節鏡的使用，進行微創手術，達到軟骨小面積缺損即時修補、避免走向退化性關節炎的目標。

Currently, the effect of treatments for osteochondral injuries is dissatisfactory. The main problem of the current treatments is most cartilage formation is fibrocartilage, which is different from the hyaline cartilage in mechanical properties and functions. The other problems with chondrocyte transplantation are poor recovery after surgery and keeping transplanted cells in defects. In recent years, tissue engineering has popularly developed. The combination of stem cells or chondrocytes in biomaterials is applied to cartilage repair, which is expected to improve the regeneration ability of cartilage tissue and the possibility of complete repair in the future. Among various biomaterials, hydrogel offers some advantages for cartilage engineering, such as high water absorption ability can improve the nutrient exchange rate; great encapsulation ability, which can be used as a carrier to transfer the cells, drugs, and growth factors to the defects for repair. Although many studies have shown that hydrogels have good results in cartilage repair, there still existed some problems need to be resolved. Mechanical properties and cell toxicity still need to be improved as proper scaffolds for cartilage repair. Therefore, this research is devoted to exploring a new kind of hydrogel with good biocompatibility and mechanical properties through hybrid-crosslinking, which is formed by temperature and photo-crosslinking polymerization.
From the FTIR and 1H-NMR analysis, the material was successfully grafted to methacrylic anhydride (MA) and NIPAAm, which has photo-sensitive and temperature-sensitive properties. In the experimental groups, they were divided into 2% and 5%NC-MA hybrid-crosslinking hydrogel, and 2%CS-MA photo-crosslinking hydrogel. SEM examinations showed that NC-MA hybrid-crosslinking hydrogels have proper porosity and microstructure. From the rheological behavior and compression test, the mechanical properties of NC-MA hybrid-crosslinking are greatly improved compared with photo-crosslinking hydrogel. The swelling ratio and degradation test displayed that NC-MA hybrid-crosslinking hydrogel has a superior nutrient exchange rate and structural stability. From the biocompatibility test and LIVE/DEAD analysis, the NC-MA hybrid-crosslinking hydrogel is non-toxicity and provides a stable environment for chondrocyte proliferation.
Among the groups, 5% NC-MA hydrogel has superior performance including rapid hydrogel formation, good porosity, better mechanical property, good cell adhesion, and no cytotoxicity. In rheological property analysis, the storage modulus has correlations with concentration and the crosslinking ability of materials. The storage modulus of 5%NC-MA is at least 10 folds higher than others. Moreover, the compression test showed that the compression modulus of 5%NC-MA could reach 109 kPa, which is 3.5 folds higher than 2%CS-MA hydrogels. The results all confirmed that hybrid-crosslinking can improve the mechanical property of hydrogels. From the CCK-8 and LIVE/DEAD analysis, the outcomes revealed good biocompatibility and chondrocytes could stably grow in 5%NC-MA hydrogel. In the biochemical and histochemical assay, there was ECM production in 5%NC-MA hydrogel.
To sum up, this hybrid-crosslinking hydrogel shows superior properties to serve as a novel cartilage repair material. In the future, it can be operated on combined with clinical arthroscopy to perform minimally invasive surgery. To attain the goal of immediately repairing when minor cartilage defects occur and avoid the progress of osteoarthritis.

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