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標題: | II-VI族發光性半導體奈米材料以及超順磁性奈米粒子的合成,鑑定以及應用 Synthesis, Characterization, and Applications of II-VI Compound Semiconductor Nanomaterials and Superparamagnetic Nanoparticles |
作者: | Chih-Wei Lai 賴志維 |
指導教授: | 周必泰 |
關鍵字: | 量子點,磁性奈米粒子,矽化合物修飾,生物應用, quantum dots,superparamagnetic nanoparticles,silica modification,bioapplications, |
出版年 : | 2009 |
學位: | 博士 |
摘要: | 本論文主要探討利用在界面活性劑的反應環境下,可以成功合成出二六族的半導體奈米粒子,與以著溶劑水熱法來合成出磁性奈米粒子之外,亦可以技巧性分別在半導體奈米粒子以及磁性奈米粒子表面做修飾化學修飾,藉此增進彼此的功能性,並且將這些功能應用出來。一開始在本篇論文中,我有比較詳細的介紹所謂半導體奈米粒子(簡稱:量子點)的相關光物理性質還有所使用的合成步驟概念。由於本實驗室已可穩定合成出硒化鎘(CdSe),碲化鎘(CdTe)量子點,進一步的我們可以利用半導體材料的彼此能隙(band gap)關係,將原本的硒化鎘包覆上不同的無機材料(如:碲化鋅, ZnTe),量子點會因為這些無機材料的包覆改變其原本的光物理性質,我們便對其放光性質做深入的光譜討探。再者,量子點由於無機材料的包覆(如:硫化鋅, ZnS)後可以增強原本內部量子點(如:硒化鎘)的放光,因此便將放光強,光穩定夠的CdSe/ZnS量子點拿來作為發展離子偵測以及生物顯影方面發展材料。首先在離子偵測方面,先將放綠光還有放紅光的奈米粒子分別修飾上15-crown-5的有機化合物,此種化合物會像三明治一樣把鉀離子夾住,如此一來修飾上15-crown-5的兩種光放光量子點會因為外加鉀離子而相互靠近,進而產生能量轉移的現象,造成這兩種量子點放光明顯的改變,達到鉀離子偵測目的。此一離子偵測的偵測極限約~10-6M。生醫顯影方面藉由氧化矽無機材料的包覆是已知可以有效降低量子點毒性的步驟之一,但是此步驟會使的原本的量子點放光因為此無機材料包覆後所產生的表面缺陷造成放光亮度大幅下降。在這裡利用在氧化矽包覆完量子點後,對其照射紫外線光源,在量子點表面產生光氧化作用,把產生的表面缺陷填補起來,使的原本被氧化矽包覆的量子點放光增強五倍以上。接著就把此毒性低的量子點運用在幹細胞的顯影上,且成功得到絕佳的幹細胞雙光子顯影效果。
在磁性奈米粒子方面,參考了國際上所發表的合成氧化鐵奈米粒子的方法後加以改善,除了利用多元醇來還原產生氧化鐵奈的例子外,還結合了水熱法的合成步驟,成功合成出大小均勻(12nm)而且室溫下磁力高達71.5emu/g氧化鐵磁性奈米子。藉著逆微胞系統的合成方式,成功的將氧化矽奈米球包覆在氧化鐵奈米粒子外面形成殼層。與清大季昀老師合作將其其實驗室合成出來具有光動力療法的銥錯合物(Ir)成功的修飾在氧化矽殼層,因此整個複合基材成功的顯現了核磁共振顯影, 磷光以及單態氧產生的機制。這種Fe3O4/SiO2(Ir)奈米粒子在進行生物測試的時候可以明顯觀察到吞噬奈米粒子的癌細胞有明顯死亡的情形。最後,我利用溶劑水熱法可以在一鍋反應中,成功得到鐵鉑包覆氧化鐵殼層(FePt/Fe3O4)磁性奈米粒子。以知鐵鉑具有殺死細胞的效用,但是其本身的磁性不高,所產生的核磁共振顯影的效果不好,因此在包覆上氧化鐵後,其本身的磁性可以提高六倍以上(e.g., ~60 emu/g),在實際細胞上的測試也得到良好的核磁共振顯影訊號,在鐵鉑材料在於細胞應用為一大突破。 In this thesis, we concentrated on the syntheses and characterization type-II quantum dots (QDs) of various core and shell materials from II-VI compound elements by a developed soft template synthesis with surfactants, such as TOPO and HDA, on two-step approaches. In the beginning, there have a detail description of Quantum dots’ synthesis and optical property in chapter 1. Then, we have succeeded to fabricate CdSe/ZnTe, CdTe/CdSe, and CdSe/CdTe/ZnTe type-II QDs. After using chemically synthesis environment to synthesize type-II QDs, the topic what we want to research is more detail studied in fundamental approaches such as relaxation dynamics and energy/charge transfer processes. Prior to present my work, a general review in terms of chronic progress, fundamental and application of nanoscience is elaborated in chapter 2. QDs with high quantum yield, well photo-stability, and facile fabrication properties can be used for bio-sensor and bio-imaging application. We have successfully prepared highly luminescent type-I quantum dots (QDs) with narrow emission spectra. Phase transfer of the QDs from organic solvents to aqueous media was also achieved. Furthermore, the two emission wavelength (540nm and 648nm) luminescent QDs were modified 15-crown-5 ligand for detection potassium ion. recognition of K+ can be achieved via the Förster type of energy transfer between two different color QDs, so that [K+] of the order of 10-6 M can be promptly observed (chapter 3). On the other hand, for reducing toxicity of QDs, we formed QDs/SiO2 core/shell nanoparticles due to silica shell of ability to avoid the cadmium ion releasing. However, it exist lower emission intensity. To overcome this problem and practice its bio-imaging ability in vitro, we prepared QDs/SiO2 with a delay photooxidation process for enhancing QY. And it indeed worked that the QDs/SiO2 with high visible and near-infrared radiation emission intensity was not toxicity in stem cell on two-photon imaging. The practical application was also elaborated in chapter 4. In chapter 5 and 6, we then switched our gear toward the synthesis and application of superparamagnetic nanoparticles. Highly uniform Fe3O4/SiO2 core/shell nanoparticles functionalized by phosphorescent iridium complexes (Ir) have been strategically designed and synthesized. The Fe3O4/SiO2(Ir) nanocomposite demonstrates its versatility in various applications: the magnetic core provides the capability for magnetic resonance imaging and the great enhancement of the spin-orbit coupling in the iridium complex makes it well suited for phosphorescent labeling and simultaneous singlet oxygen generation to induce apoptosis. On the other hand, via a facile, we found that high pressure, high temperature, solvothermal approach makes FePt/Fe3O4 nanoparticles synthesis much more facile. Moreover, the resulting FePt/Fe3O4 MNPs possess several unique properties such as great enhancement of magnetization (e.g., ~60 emu/g at 5 kOe under applied field.), intact surface passivation and hence great dispersibility as well as the feasibility in the transformation toward water soluble MNPs. After phase transfer, the water soluble FePt/Fe3O4 MNPs have been successfully applied in MRI. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/26003 |
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