應用修飾螢光分子之中孔洞二氧化矽奈米粒子進行癌細胞內酸鹼值偵測與三維空間即時追蹤

酸鹼值在細胞生理系統中扮演極重要的角色，從細胞增生、胞吞作用(endocytosis)到細胞凋零都伴隨著酸鹼值改變，因此一個能精確偵測細胞內酸鹼值變化的偵測器是探討細胞生理學不可或缺的重要利器。近年來，具有高生物相容性、高表面積且易於在表面修飾各種官能基的中孔洞二氧化矽奈米粒子，在各研究領域都受到相當廣泛的討論。在此研究中，我們建立了一個統合的細胞內單粒子追蹤與酸鹼值偵測系統，突破過去文獻中只能專一在其中一項技術的限制。在材料方面，利用將螢光分子fluorescein isothiocyanate (FITC) 與rhodamine B isothiocyanate (RITC) 以共縮合方式鑲嵌於二氧化矽中孔洞奈米粒子的結構當中，其中FITC在鹼性環境下螢光強度會增加，而RITC的螢光強度則不受環境酸鹼值影響，再利用其強度比值去做換算便能得知該環境的酸鹼度。本篇論文的第一部分我們使用三維空間即時單粒子追蹤技術，去追蹤癌細胞對於修飾螢光分子之中孔洞二氧化矽奈米粒子的吞噬行為與粒子所在環境的酸鹼值。透過觀察胞吞作用以及粒子脫離核內體(endosome)的過程，我們發現周遭環境酸鹼值改變與粒子運動行為有密切關連，而這些行為同時也受到細胞生理狀態的影響。論文第二部分則希望能改善過去的酸鹼值偵測器過於狹窄的偵測範圍，使其能準確地反映周遭環境變化。藉由合成具有中空結構和大小不一的表面孔洞的螢光中孔洞二氧化矽奈米粒子，我們利用這些曲率不一致的表面來影響FITC與材料表面帶正電荷官能基之間的距離，進而改變其酸解離常數(pKa)且增廣FITC螢光強度變化所涵蓋的pH值範圍，讓此奈米粒子成為具備極佳發展潛能的細胞pH偵測器。未來希望能將此細胞酸鹼值偵測器與追蹤技術應用於更多生物現象的觀察，以冀求對於細胞生理機制能有更進一步之了解。

關鍵字

中孔洞二氧化矽；癌細胞；酸鹼值偵測器；三維空間即時追蹤；胞吞作用

並列摘要

Intracellular pH plays many important roles in cell, including proliferation, apoptosis and endocytosis. Therefore, information of intracellular pH can help us to understand the cellular dysfunctions and the physical conditions of organelles. Since the discovery of mesoporous silica nanoparticle (MSN), such silica materials with controllable physical properties and excellent biocompatibility have received tremendous attention. Because the silanol groups on surface are available for further modification of diverse functional groups, MSN has been employed in drug delivery, intracellular imaging and sensing. Herein, dye-leaded MSN is synthesized by co-condensing a pH-sensitive dye FITC and a reference dye RITC with silica source. By ratiometric method, one can correctly obtain the readout of this pH sensor. In the first part of the thesis, we demonstrate a 3D real time tracking technique which can record the trajectories of the fluorescent dye-loaded MSN (FMSN) internalized by cancer cell and the change of pH at the same time. The motion of FMSN and pH are proved highly correlative by observing the acidification after endocytosis and the increase of pH due to endosome escape. Moreover, the cellular dysfunction is shown responsible for the occurrence of endosome escape. In the second part, we synthesize hollow structured FMSN by adding hexane during the synthesis, which also leads to a broad pore size distribution. The different surface curvature due to various pore sizes affects not only the distance between FITC and positive-charged functional groups on the silica surface but the pKa value of FITC. As a result, we obtain a powerful pH sensor which owns a broad pH sensing range. We envision these researches can open up new designs of sensors and improve the knowledge of cellular process.

並列關鍵字

Mesoporous silica ； Cancer cell ； pH sensor ； 3D Real Time Tracking ； Endocytosis

參考文獻

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應用修飾螢光分子之中孔洞二氧化矽奈米粒子進行癌細胞內酸鹼值偵測與三維空間即時追蹤

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