Cell culture is an important issue in tissue engineering. The temperature-sensitive hydrogel, poly (N-isopropylacrylamide) (PNIPAAm) hydrogel, due to its lacking mechanical strength and properly cell culture surface, is limited to culture cells in tissue engineering application. In this study, multi-walled carbon nanotubes (MWCNT) and multi-walled carbon nanotubes-poly-L-ornithine (MWCNT-PLO) were impregnated into PNIPAAm hydrogels to form cell culture substrates. We have successfully prepared the modified PNIPAAm hydrogels , PNIPAAm-MWCNT (0.245, 0.49, 0.735wt%) and PNIPAAm-MWCNT-PLO (0.245, 0.49, 0.735wt%). By Fourier transform infrared spectroscopy, we identified the functional groups of PNIPAAm, PLO and MWCNT. Using scanning electron microscopy to observe the surface of hydrogel, it was revealed that the surface pores of the MWCNT or MWCNT-PLO impregnated PNIPAAm hydrogels would increase with increasing the amounts of carbon nanotubes. Simultaneously, the pattern of the pore shape gradually became round from long and narrow. It was also revealed that hydrophobicity , viscoelasticity, and swelling ratio would increase by increasing the amounts of carbon nanotubes. From the results, PNIPAAm-MWCNT hydrogel was found to be the better substrate compared to PNIPAAm-MWCNT-PLO for the cell adherence and the cell detachment to get cell sheets by culturing Madin-Darby canine kidney (MDCK) cells.
In conclusion, this study demonstrated that the impregnated MWCNT could affect the mechanical strength of PNIPAAm hydrogel to improve cell adherence. The cell sheets could be successfully and spontaneously detached by changing temperature and harvested from the PNIPAAm-MWCNT hydrogels or PNIPAAm-MWCNT-PLO hydrogels. It is expected that PNIPAAm-MWCNT hydrogel would become a novel cell culture substrate or scaffold for cell therapy in tissue engineering in the near future.

細胞培養是組織再生的重要入門課題之一，在利用感溫型高分子(poly(N-isopropylacrylamide)(PNIPAAm))培養層片細胞的研究中，會因此材料本身缺乏機械強度，而受限其於組織工程的應用。本研究利用多壁奈米碳管(multi-wall carbon nanotubes(MWCNT)及multi-wall carbon nanotubes-poly-L-ornithine(MWCNT-PLO))植入於PNIPAAm水膠形成細胞培養基材，對於細胞貼附與去貼附之效果。本研究探討與比較三種細胞培養基材: PNIPAAm hydrogel，PNIPAAm-MWCNT hydrogel以及PNIPAAm-MWCNT-PLO hydrogel，分別進行鑑定與分析，並探究這三種基材對層片細胞培養的效果。
本研究成功地合成植入不同比例MWCNT及PLO於PNIPAAm製成PNIPAAm-MWCNT(0.245, 0.49, 0.735wt%)與PNIPAAm-MWCNT-PLO(0.245, 0.49, 0.735wt%)水膠，經由紅外線光譜儀分別鑑定出兩者應具有之官能基。藉由掃描式電子顯微鏡觀察水膠表面，發現植入MWCNT或MWCNT-PLO的水膠其孔洞度隨著奈米碳管濃度的增加而趨向增多，且孔洞的型態由窄長型逐漸成為圓形，並隨著奈米碳管添加的量增加，水膠的膨潤比、疏水性也會增加，但黏彈性會下降。將以上合成好的水膠，嘗試做為培養細胞的基材，發現PNIPAAm-MWCNT水膠有最佳的細胞貼附型態，而在細胞去貼附的結果中，擁有最佳的細胞貼附基材可得到完整的細胞層片，而PNIPAAm-MWCNT-PLO水膠亦有細胞貼附及去貼附的效果，但其細胞量為PNIPAAm-MWCNT水膠的一半。
綜合以上，本研究利用多壁奈米碳管的添加，使表面的孔洞度增加、孔洞型態改變、膨潤度增加、黏彈性下降，讓細胞成功的貼附在水膠表面，且添加多壁奈米碳管後的PNIPAAm水膠同樣可維持其溫度敏感特性，以得到細胞層片。在生醫材料的領域裡，期望能成為新的細胞培養基材或支架。

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