中孔洞材料在二氧化碳捕獲與藥物釋放之研究

Abstract

本論文中，使用各種不同的合成技術，其中包括溶膠-凝膠法、水熱尿素反應、微波輔助合成法以及固態反應開發出多功能性中孔洞奈米結構材料 (CaO/CaAlO, C12Al14O33, Gd2O3, TiO2)。使用粉末X光繞射儀(PXRD)、穿透式電子顯微鏡/電子能量損失光譜 (TEM/EELS)、掃瞄式電子顯微鏡/X光能量分散光譜儀(SEM/EDS)、傅氏轉換紅外線光譜(FTIR)、氮氣吸附等溫線(N2 adsorption isotherm) 詳細地鑑定這些材料的組成、形貌、化學結構以及多孔結構。這些中孔洞奈米結構材料的合成機制將於各章節中被討論。本研究的中孔洞材料的孔徑大小為2-50奈米範圍內。由於它們具有高表面積與奈米孔洞結構的諸多優點，在二氧化碳捕獲與藥物釋放領域分別可以被設計為一種高溫吸附劑或藥物載體。 在先期研究發現 (如附錄-1)，首先採用水熱共沉法合成出二種不同金屬混合之金屬氧化物(MgAlO、CaAlO、SrAlO)，並且在高溫(200-850 oC)二氧化碳補捉實驗證實，CaAlO金屬氧化物最適合作為高溫二氧化碳吸附劑(600-700 oC)。因此，使用水熱尿素法來合成中孔洞金屬氧化物(CaO/CaAlO)，此材料具有高表面積、均一孔洞結構及均勻的奈米氧化鈣分佈，經由熱重分析(TGA)或固定床反應器(fixed-bed reactor)同時進行二氧化碳補捉實驗，結果證實中孔洞奈米材料具有高二氧化碳吸附容量，快速吸附性和長循環壽命。更進一步，使用微波輔助合成法進行中孔洞CaAlO金屬氧化物合成，由粉末X光繞射與電子顯微鏡證明，在低於600 oC的固態反應後可以形成結晶性C12Al14O33奈米棒成長在奈米孔洞CaAlO基質表面上。此材料具有多孔結構與高熱穩定性，未來可以作為催化劑或二氧化碳吸附劑之載體。 另外，本研究採用溶膠-凝膠法合成出中孔洞氧化釓(Gd2O3)奈米管及中孔洞二氧化鈦(TiO2)奈米薄膜，兩者材料可作為藥物載體並使用於藥物釋放控制。此材料鑑定具有高表面積、多孔洞結構與高結晶性的奈米骨架。中孔洞氧化釓奈米管表現出微弱的超順磁特性，能夠攜帶布洛芬(IBU)藥物，並且通過外部磁場控制方式進行藥物釋放。另外，二氧化鈦薄膜具有蠕蟲狀中孔洞結構，使用布洛芬(IBU)和萬古黴素(VAN)作為藥物模型分子，測定與薄膜化學相關持續藥物釋放。除此之外，體外骨細胞的黏附行為和氫氧基磷灰石形成，證明此薄膜也具有細胞相容性和生物活性表現。

In this dissertation, multi-functionalized mesoporous nanostructured materials (such as CaO/CaAlO, C12Al14O33, Gd2O3, and TiO2) have been prepared through various synthesized routes, which include sol-gel method, hydrothermal urea reaction, microwave-assisted synthesis, and solid-state reaction. The composition, morphology, chemical structure, and porous structure of these materials were identified in detail using powder X-ray diffraction (PXRD), transmission electron microscopy/electron energy loss spectroscopy (TEM/EELS), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), and N2-adsorption isotherm. The synthesized mechanisms of these materials are discussed in respective chapter. In this study, the obtained mesoporous materials exhibit pore diameter in the range of 2-50 nm. Due to many advantages of its high surface area and nanopores structure, these mesoporous nanostructured materials can be designed as high-temperature CO2 sorbents and drug carriers in the fields of carbon dioxide capture and drug delivery, respectively. A preliminary study (see Appendix-1) can be found that hydrothermal coprecipitation method was first used to synthesize the metal oxide compounds (MgAlO, CaAlO, and SrAlO), and experiments for carbon dioxide capture at high temperatures (200-850 oC) have proved that the CaAlO metal oxide is the most suitable as a high-temperature carbon dioxide sorbent (600-700 oC). Therefore, mesoporous metal oxides (CaO/CaAlO) were prepared by a hydrothermal urea method and this material demonstrates high surface area and uniform pore structure and nano-sized calcium oxide distribution. The results of carbon dioxide capture experiment by thermal gravimetric analysis (TGA) or fixed-bed reactor show that mesoporous nanomaterials has high carbon dioxide adsorption capacity, fast adsorption and long cycle life. Furthermore, the use of microwave-assisted synthesis to synthesize mesoporous CaAlO metal oxides, which can be identified by powder X-ray diffraction and electron microscopy. The results showed that the growth of the crystalline C12Al14O33 nanorods on the surface of nanoporous CaAlO matrix can be formed in the solid-state reaction of less than 600 oC. In the future, this material with pore structure and high thermal stability can be used as a support for the catalyst or CO2 sorbent. In addition, the study is also focused on the mesoporous gadolinium oxide (Gd2O3) nanotubes or mesoporous titanium dioxide (TiO2) nano-thin film, which was fabricated by the sol-gel routes, both materials can be used as a drug carrier for controlled drug release. The characterization of the material in this study has been identified to exhibit a high surface area, porous structure and high crystalline nano-frameworks. Mesoporous Gd2O3 nanotubes exhibited weak superparamagnetic property and was found to be able to carry and elute a model molecule, i.e. ibuprofen (IBU), in a controllable manner via an external magnetic field. Further, the worm-like mesoporous architecture associated with the chemistry of the TiO2 film, a sustained drug release using ibuprofen (IBU) and vancomycin (VAN) as model molecules from the film also was determined. Beside, adhesion behavior of osteoblast cells, together with an in vitro apaptitic formation substantiated the cytocompatibility and bioactivity of the mesoporous TiO2 films.