多孔性明膠-幾丁聚醣/奈米二氧化矽複合支架材料製備與特性研究

Abstract

本研究以溶膠凝膠(sol-gel)法製備奈米二氧化矽，並與具有優良生物可降解性/生物相容性之生物高分子明膠與幾丁聚醣摻混反應，在經由冷凍乾燥法製備多孔性明膠-幾丁聚醣/奈米二氧化矽複合支架材料，以作為骨組織工程，具三維空間結構之多孔支架材料，並針對複合支架進行一系列之特性探討。 本實驗藉由有機-無機奈米複合材料之觀點，以無機物奈米二氧化矽扮演支架材料補強的角色，並藉由明膠-幾丁聚醣高分子與二氧化矽的交聯鍵結，以改善天然高分子支架材料機械性質與熱穩定性不佳的缺點，以及降緩天然高分子明膠於體溫下會快速降解的特性，也避免支架材料合成過程中，交聯劑的殘留對組織生長造成毒害的問題。並藉由浸泡法於多孔性複合支架表面披覆生成仿骨骼組織具生物活性誘導因子之氫氧基磷灰石(HA)，以提升支架材料的生物活性與細胞界面的相容性。 複合支架材料的特性分析結果顯示，傅利葉紅外線光譜儀(FTIR)檢測結果顯示，生物高分子明膠-幾丁聚醣與奈米二氧化矽的摻混反應，確實有形成交聯鍵結的產生；場發射電子顯微鏡(FE-SEM)觀察結果顯示:(1)無機物奈米二氧化矽微粒之平均粒徑大小為70nm；(2)由冷凍乾燥法製備之明膠-幾丁聚醣/奈米二氧化矽複合支架材料，其型態為相互交聯的孔洞結構，當支架成分為3 phr二氧化矽、6 phr明膠與1.5 phr幾丁聚醣時，達到最佳的孔洞交聯結構與均一的孔洞大小；(3)浸泡法所生長之HA晶體成核於多孔支架的孔壁上，且隨明膠與幾丁聚醣含量的上升而增加。以熱差掃描分析儀(DSC)、熱重損失分析儀(TGA)，探討複合支架的熱性質結果顯示，無機物奈米二氧化矽的加入，以及天然高分子明膠、幾丁聚醣與二氧化矽三者間的交聯鍵結，不但提升支架的熱性質，也降緩複合支架材料的生物降解速率，以及提升支架孔洞結構的抗壓強度，達到骨組織工程對細胞支架的要求。物理性質檢測結果得知，多孔的複合支架結構，其孔隙率皆高達85%以上，吸水率高達300-500％之間，其達到骨組織工程多孔支架材料的需求。而支架的膨潤性於支架成分為3 phr二氧化矽、6 phr明膠與1.5 phr幾丁聚醣時，其有最低的膨潤度約4%，達到組織工程支架材料膨潤度低於5%之需求。毒物性測試結果顯示，複合支架材料的製備過程，界面活性劑的殘留，導致細胞有輕微毒性的反應。

In this study, SiO2 nanoparticles prepared by the sol-gel technique were incorporated with biopolymer gelatin and chitosan biopolymers containing high biodegradability and biocompatibility. Then, the gelatin-chitosan/SiO2 composite scaffolds with three-dimensional porosity prepared by freeze-drying technique can be used in bone-tissue engineering and were characterized by a series of analysis. Organic-inorganic nanocomposites usually contain excellent thermal and mechanical properties compared to those of pure material. Therefore,the gelatin-chitosan/SiO2 composite were expected to improve the poor mechanical properties and thermal stability of organic matrix using inorganic SiO2 nanoparticles. The bioactivity and interfacial compatibility between cells of fabricated composite scaffold can be induced by growing hydroxyapatite (HA) using biomimetic process. From the result of Fourier Transform Infrared Rays Spectrometer (FTIR), it indicated that the interfacial interaction between gelatin-chitosan and SiO2 nanoparticles occurred. The particle size of SiO2 and morphology by Field-Emission Scanning Electron Microscope (FE-SEM). These results show the average particle size of SiO2 is about 70 nm and the morphology of composite containing 3 phr SiO2, 6 phr gelatin and 1.5 phr chiotsan shows uniformly three-dimensional porosity with cross linking conformation. The induced HA particle was increased by increasing the concentration of gelatin-chitosan. The thermal stability and mechanical properties of fabricated composite scaffold indicate significant improvement compared to that of pure organic matrix. The porosity, water absorption and swelling ratio of scaffold can be reached over 85%, 300~500% and 4% respectively. These data reveal the fabricated scaffold have reached the requirement of bone-tissue engineering for scaffolds. The toxicity test of prepared materials show the residual surfactant had slightly toxic effect on cells.