Utilizing Fluorescent Dye Loaded Mesoporous Silica Nanoparticle for pH Sensing and 3D Real Time Tracking in Cancer Cell

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。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.口試委員會審定書 # 謝誌 I 中文摘要 II Abstract III Table of Contents i List of Figures vi List of Tables xv List of Schemes xvi Chapter 1 General Introduction 1 1.1 Introduction to Mesoporous Silica Nanoparticle (MSN) 1 1.1.1 Synthesis Mechanism of MSN 3 1.1.2 Applications of MSN 6 1.2 Introduction to Hollow Mesoporous Silica nanoparticles (HMSNs) 9 1.2.1 Synthesis of HMSNs 9 1.2.2 Applications of HMSN 12 1.3 References 14 Chapter 2 Simultaneous 3D Single Particle Tracking and Ratiometric Local pH Detection in Cancer Cells 19 2.1 Introduction 19 2.2 Experimental Section 25 2.2.1 Materials 25 2.2.2 Characterization 27 I. Transmission Electron Microscopy (TEM) 27 II. Nitrogen Adsorption-Desoprtion Isotherms 27 III. Fluorescence Spectrum 28 IV. X-ray Diffraction Pattern 28 V. Dynamic Light Scattering (DLS) 28 VI. Zeta Potential 29 2.2.3 Synthetic Procedure 30 I. Preparation of Dye Conjugated APTMS 30 II. Synthesis of TA-FMSNs 30 III. Synthesis of THPMP-FMSNs 32 2.2.4 Fluorescence Microscope Setup 34 2.2.5 Calibration Curves 36 I. Z-Axial Position Calibration 36 II. pH Calibration 36 2.2.6 In Vitro Cell Studies 38 I. Cell Culture 38 II. Single Particle Tracking and Spectroscopy in Live Cell 39 III. Drug Treatment 39 2.3 Results and Discussions 40 2.4 Conclusion 69 2.5 References 70 Chapter 3 A Broad-range fluorescent pH Sensor Based on Hollow Mesoporous Silica Nanoparticles with Surface Curvature Effect 73 3.1 Introduction 73 3.1.1 Measuring Intracellular pH by Fluorescence 73 3.1.2 Broadening the Sensing Range of Nano-sized pH sensor 79 3.1.3 pH Biosensor Based on Mesoporous Silica Nanoparticles 82 3.2 Experimental Section 84 3.2.1 Materials 84 3.2.2 Characterization 86 I. Transmission Electron Microscopy (TEM) 86 II. Nitrogen Adsorption-Desoprtion Isotherms 86 III. Fluorescence Spectrum 87 IV. X-ray Diffraction Pattern 87 V. Dynamic Light Scattering (DLS) 87 VI. Scanning electron microscope (SEM) 88 VII. Zeta Potential 88 3.2.3 Synthetic Procedure 89 I. Preparation of Dye Conjugated APTMS 89 II. Synthesis of Dye-HMSN 89 III. Synthesis of Dye-MSN 90 IV. Synthesis of HMSN Using Ethanol (EX-s) 91 V. Synthesis of HMSN Using THF (TYDZ) 92 VI. Synthesis of Dye-loaded Mesoporous Products 93 3.2.4 In Vitro Cell Study 94 I. Cell Cuture 94 II. Incubation of HeLa cells with Dye-HMSNs 95 III. Confocal Microscope Study 95 IV. Establishment of Calibration Curves 96 3.3 Results and Discussion 97 3.3.1 Comparing Dye-MSN with Dye-HMSN 97 I. Results of Characterization 97 II. Hypothesis of the Broad pH-Sensing Capability 103 3.3.2 Mechanism Study 105 I. Characterization of the HMSNs 105 II. Solvent Effect 112 III. Broad-Ranging pH sensors 117 3.3.3 Intracellular pH study 126 3.4 Conclusions 131 3.5 References 132 Chapter 4 Conclusion 13