官能化中孔洞二氧化矽薄膜於不同孔洞結構及表面修飾下於控制釋放之應用

Abstract

中孔洞材料自1990年代以來受到廣泛的研究，其原因乃受惠於材料本身的獨特性質，如高比表面積、高孔洞體積、可調整孔洞大小等。目前中孔洞材料已經可以製備成不同的形貌，如塊材、纖維、奈米顆粒、薄膜等。此論文將針對中孔洞薄膜進行的合成及藥物釋放之應用。 此實驗以中孔洞二氧化矽薄膜為基材，作為藥物釋放之系統並進行釋放行為之研究。模擬藥物則以螢光染料，FITC，作為測定目標。實驗分別探討孔洞結構及化學官能化對於釋放行為的影響。在孔洞結構方面，我們討論二維及三維六角結構(2D hexagonal and 3D hexagonal mesostructures)等兩種中孔結構。在化學官能化方面，則個別探討不同化學官能基改質之薄膜對於釋放行為的影響，探討目標包含：物理吸附、物理性摻雜、可斷式化學鍵。此外，我們配合釋放模型解釋加以解釋其釋放行為。 物理吸附方面，由恆溫吸附實驗中發現三維六角孔洞結構具有較低的吸附量。此現象是因為在複雜孔洞結構中，在孔洞開口附近堆積的染料分子容易產生質傳障礙，使接下來的染料分子不易進入到孔洞內部，最後造成染料吸附量減低。而在釋放行為方面，二維及三維六角結構皆為一級釋放(first-ordered kinetics)，其釋放行為乃由孔洞內的擴散控制，且並無太明顯的差異，此乃因為染料分子在兩者結構中仍可以自由移動擴散，故孔洞結構並不造成釋放之差異。 在物理性摻雜中，染料分子均勻散佈在二氧化矽骨架(framework)中，此時釋放行為零級釋放(zero-ordered kinetics)，其擴散行為由染料從骨架溶解之步驟決定。 而利用可斷式雙硫鍵修飾中，其釋放具有兩個階段；第一階段釋放為零級釋放，乃是由未鍵結在雙硫鍵之FITC染料分子經由溶解所釋放，而第二階段釋放可經由加入雙硫鍵還原劑切斷雙硫鍵，達到精確控制釋放時間之目的。 此研究可使釋放行為達到穩定、長效、釋放時間可控制之目的，未來可望成為細胞工程或生物感測器之重要元件。

Mesoporous materials have been studied extensively since 1990s because of their special characters, for example, high surface area and pore volume, and tunable pore size. Up to now, mesoporous materials can be fabricated in variable morphologies such as bulk, fiber, nanoparticles, and film. This thesis includes the synthesis and application of mesoporous silica thin films. This project took mesoporous silica thin films as drug-delivery matrix and fluorescent dye (FITC) as model drug to study the release behavior of FITC. The experimental variables include mesostructures and chemical functionalities. The mesostructures include 2D hexagonal and 3D hexagonal. The functionalizations include immersion (physical adsorption), physical doping, and cleavable binding. In addition, release model is applied to explain the release behavior. This study can reach release in a stable, long-term, and controlled release behavior at specific timing. In the future, it is potential to be the substrate of cell engineering and the device of biosensor. In immersion, the 3D hexagonal mesostructure loaded less amount of FITC dye in the experiment of binding isotherm. Because in complex pore structure, the heaped FITC dye molecules at pore entrance produce barrier of mass transport; the barrier hinders the loading of following FITC molecules into internal pores. As a result, the loading amount decreases. In release behavior, both mesostructures show first-ordered kinetics. Because the release in governed by the diffusion inside pores and the dye molecules can diffuse freely inside pores, the mesostructures do not impact release seriously. In physical doping, FITC dye disperses uniformly in silica framework. The release obeys zero-ordered kinetics, representing the release is governed by the dissolution of FITC dye from silica framework into PBS solution. In cleavable binding, the release includes two stages. The first-stage release is zero-ordered kinetics, and that is from the FITC molecules that do not bind to disulfide linker. The second-stage release can be controlled by adding disulfide reduce reagent to approach controlled release at precise time.