Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/9566
標題: 聚乳酸/蒙脫土奈米複合材料支架製備與物性及生物反應性研究
Poly(lactic acid)/montmorillonite nanocomposite scaffolds: Fabrication, characterization and biological properties
作者: 吳政陽
Wu, Cheng-Yang
關鍵字: PLA;聚乳酸;scaffold;composite;支架;複合材料
出版社: 材料工程學研究所
摘要: 
本研究為製備生醫用途之高分子材料,使用了生物可分解高分子聚乳酸(PLA),而聚乳酸本身因其熱穩定性及機械性質不佳等缺點,因此加入擁有高度剛性的蒙脫土(MMT)做為補強,並將補強後的材料利用鹽析法製備出多孔支架。
MMT先經過界面活性劑CATB及chitosan等的有機改質後,除了表面的親水性改質為較接近PLA表面的親油性外,層間距離由原先的12.8A°提升至41.73A°。有機改質MMT再經由溶液法與PLA混合後,由XRD的結果顯示呈現分散均勻的情況,且可經由TEM的觀察證實已成功製備出脫層型的奈米複合材料,但在較高的改質MMT含量摻雜後,則呈現部分插層,部分脫層型之奈米複合材料。
將上述製備出之PLA奈米複合材料及支架,表面披覆具有與人體骨骼相類似結構之磷酸鈣,再將此樣品浸泡於SBF中,可進一步披覆不同表面型態之磷酸鈣。由浸泡CaCl2+(NH4)2HPO4水溶液之實驗結果發現,數種參數在披覆時間同為一天的情況下,於pH=8,溫度=37.5℃時有最佳的披覆條件;再將上述樣品浸泡SBF於一天後,已可發現表面披覆磷酸鈣晶體,顯示了有先經過CaCl2+(NH4)2HPO4水溶液浸泡所披覆之磷酸鈣形成速率較快,經由XRD及EDX證實,為氫氧基磷灰石(hydroxyapatite, HA)結構。並對其進行牛血清蛋白(BSA)之吸附,以初步鑑定其生物相容性。由ATR-FTIR及FE-SEM的結果顯示,有BSA吸附之訊號存在。
再將上述製備出之PLA奈米複合材料及支架進行生物裂解實驗,裂解環境為磷酸鹽緩衝溶液,並添加酵素PPL以催化裂解:在PLA/MMT奈米複合材料方面,經由FE-SEM的觀察,試片表面在裂解後開始有孔洞出現。經由GPC的結果顯示,分子量均有隨裂解時間增加而下降的趨勢;也同時由DSC及XRD的觀察結果顯示,結晶度有隨裂解時間增加而增加之趨勢。在PLA/MMT支架方面,經由重量損失測試的結果發現在28天以後由於表面的多孔結構,產生很明顯被分解的現象,由GPC的結果顯示,分子量也有損失的趨勢,FE-SEM的結果顯示,在裂解28天以後,表面的多孔結構已被嚴重破壞,DSC及XRD結果顯示,結晶度在裂解35天後大量提升,推測樣品被分解為較小分子後,分子鏈有利於排列或移動所致。

Poly(lactic acid) has received considerable attention as a potential replacement for conventional polymer due to its biodegradability and favorable miscibility with other polymers. It is currently being investigated for biomedical application, pharmaceutical controlled release systems and in biodegradable packaging materials. However, the technological development of PLA in this area is limited by its poor thermal stability and mechanical properties. Thus several studies have been devoted to organic/inorganic nanocomposites with the aim to improve their properties.
In this study, we have used organically modified montmorillonite(MMT) as a dispersed phase to prepare the PLA/MMT nanocomposites. The fabricated PLA/MMT nanocomposites were then formed the PLA/MMT scaffolds using NaCl-leaching technique. Both X-ray diffraction data and TEM micrographs of PLA/MMT nanocomposites indicate most of the swelling silicate layer are exfoliated and randomly dispersed into PLA matrix. The PLA/MMT nanocomposites and scaffolds were found to be a bioactive material, as it formed calcium phosphate in the form of hydroxyapatite deposits in a simulated body fluid (SBF). The physical properties and biocompatibility of fabricated nanocomposites and scaffold can also be measured by DMA, GPC, FE-SEM, DSC and XRD.
From the results of FE-SEM after decomposition for 28 days, the porous structure of PLA/MMT nanocomposites and scaffolds were significantly destroyed and the results were consistent with the data of GPC. Interesting, the crystallization of PLA/MMT nanocomposites and scaffolds increase as increasing decomposition period indicating the better polymer chain arrangement after decomposition.
URI: http://hdl.handle.net/11455/9566
Appears in Collections:材料科學與工程學系

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