金與二氧化鈦奈米粒子之合成、表面修飾及其應用

Synthesis, Surface Modification, and Applications of Nanomaterials: Gold and Titanium Dioxide

李昆鴻(Kun-Hong Li)

指導教授 ： 張煥宗

國立臺灣大學/理學院/化學研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.01721

摘要

隨著奈米科技的進步，許多相關性的研究也隨之日新月異與蓬勃發展。本論文之研究目的在於製備不同的金銀奈米材料與二氧化鈦奈米粒子(titanium dioxide nanoparticles, TiO2 NPs)，並將其應用於分析胺基硫醇分子(aminothiols)與多酚類化合物(polyphenolic compounds)。另一方面，我們也嘗試利用毛細管電泳搭配雷射誘導螢光(CE-LIF)的技術來探討不同序列之DNA分子與汞離子之間的作用。論文的第一部份簡述了奈米材料的製備、物理及化學性質同時也介紹了與本論文相關之實驗技術。在第二部份的研究中我們利用尼羅紅(Nile red)修飾的金奈米粒子(NR-Au NPs)來瞭解硫醇分子與金奈米粒子之間的相互作用。藉由觀察硫醇分子加入NR-Au NPs溶液中所產生的螢光變化，不同硫醇分子的吸附速率可以利用Langmuir isotherm model來推算得知。而從實驗結果可以得知硫醇分子的吸附速率與本身的立體結構與電荷有關，同時也取決於奈米粒子的粒徑大小。此外，對於NR吸附在金奈米粒子的表面上進而形成NR產物的催化反應也在本章節中被詳細的探討。第三部份的研究主要是利用晶種促進成長法(seed-mediated growth method)在玻璃基材上製備各種金和銀奈米材料。藉由調控金和銀的晶種濃度我們可在基材上製備出高產率(27% 和54%)、高均勻性以及大尺寸(1.36 和5.21 μm)的金和銀奈米材料。藉由暗場顯微鏡(dark-field microscopy, DFM)與掃瞄式電子顯微鏡(scanning electron microscopy, SEM)的量測，這些在基材上已製備好的奈米材料可以被快速的觀察與鑑定。除此之外，從單一金屬的散射光譜圖也可以清楚地瞭解每一種奈米材料之表面特性。最後，將此製成方法與DFM的分析技術做一結合，則可以成功地在基材表面上進行高通量(high-throughput)的製備與鑑定金奈米材料的大小與形狀。第四部份的研究則是選擇TiO2 NPs作為表面輔助雷射脫附游離質譜法(surface-assisted laser desorption/ionization mass spectrometry, SALDI-MS)的基質並具備探針性質可以選擇性的偵測兒茶素分子(catechins)。透過TiO2 NPs對烯二醇類(enediol)官能基化合物之高親和作用力與藉由能量轉移所增強吸收紫外光之特性，TiO2 NPs 可有效地當作SALDI-MS的輔助基質來對兒茶素分子進行選擇性的分析。此分析方法已被證實可以成功地應用於分析與定量茶類中之兒茶素、維他命C與茶胺酸分子，亦即表示此技術未來應用於生命科學之極大潛力。最後一部份的研究則是利用CE-LIF的技術來探討DNA分子在汞離子的作用下其分離的結果並試著開發一簡單及快速分離小片段單股DNA的方法。其原理主要為透過汞離子與胸腺嘧啶(thymine, T)鹼基之間所形成的的特殊鍵結T-Hg2+-T來調控這些DNA分子的構形，再利用毛細管中填充之中性的聚合物溶液(聚環氧乙烷，簡稱PEO)來篩分這些DNA分子。隨著改變分離溶液中汞離子的濃度，4條DNA分子T33, C5T28, T5C5T23和 T15C5T13可在20分鐘內被逐漸的解析開來，且其分離時間之相對標準偏差小於2.5%。此4條DNA分子在分離過程中所產生的電淌 (mobility)差異除了與汞離子所誘導的構形不同有關，同時DNA分子與汞離子作用之後所產生的電荷密度差異也會影響其分離的結果，而此推論隨後也藉由螢光及圓二光偏極光譜(circular dichroism)的量測來得到證實。

關鍵字

金奈米粒子 ； 二氧化鈦奈米粒子

並列摘要

With the growing advances in nanotechnology, a number of interesting related researches have been demonstrated. In this thesis, we mainly focus on the preparation of different kinds of nanomaterials including gold, silver, titanium dioxide, and on their applications to the analysis of aminothiols and polyphenolic compounds. In addition, capillary electrophoresis (CE) in conjunction with laser-induced fluorescence (LIF) has been conducted to study the interactions of DNA with Hg2+. We briefly describe preparation, physical and chemical properties of nanomaterials as well as introduce related techniques used in this thesis in Chapter 1. In Chapter 2, the interactions between a variety of thiols and Nile Red-adsorbed gold nanoparticles (NR-Au NPs) by monitoring the fluorescence changes of NR-Au NPs solutions are described. Using the Langmuir isotherm model, the displacement rate constants of the NR product from the Au NP surface are estimated. Our results reveal that steric effects and the charge density of the thiols both play important roles in determining the interactions with NR-Au NPs. The interactions are also dependent on the size of NR-Au NPs. Furthermore, the catalytic characteristics of Au NPs have also been proposed through the formation of an NR product from NR upon the Au NP surface. In Chapter 3, we demonstrate the preparation of Au and Ag nanomaterials from their corresponding colloidal seeds on glass substrates via a seed-mediated growth method. By carefully controlling the concentrations of Au and Ag nanoparticle seeds, different sizes and shapes of Au and Ag nanomaterials with narrow size distribution, higher yields (27% and 54%), and larger sizes (1.36 and 5.21 μm) can be prepared. Through dark-field microscopy (DFM) and SEM measurements, the thus-prepared nanomaterials were easily and rapidly characterized. From the scattering spectra of single Au and Ag nanomaterials, we obtaibned more detailed information about their morphologies. Combining our synthetic method with DFM system, the high-throughput preparation and characterization of differently sized and shaped Au nanomaterilas on a glass substrate can be achieved. We discuss use of titanium dioxide nanoparticles (TiO2 NPs) as selective probes and matrices for the determination of catechins through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) in Chapter 4. Due to the high specificity of TiO2 NPs towards enediol-containing compounds as well as their strong absorption characteristics through efficient energy transfer, TiO2 NPs serve as affinity probes and as effective LDI matrices for the SALDI-MS determination of catechins. This method has been validated in the analysis of catechins, ascorbic acid and theanine in tea samples, showing its great potential for applications in life sciences. In Chapter 5, we discuss a simple and fast CE-LIF method for separation of short ssDNA fragments in the presence of Hg2+. Through the specific interaction of Hg2+ ions with thymine-thymine (T-T) base pairs of the DNAs, four ssDNA, including T33, C5T28, T5C5T23, and T15C5T13 were successfully separated by CE using poly(ethyleneoxide) (PEO) solutions. The separation of the four DNA fragments were completed within 20 min, with the relative standard deviation values all less than 2.5%. The Hg(II)-induced changes in conformation and charge density in the DNA are responsible for their changes in mobility during separation. Our reasoning is further supported by the fluorescence and ellipticity spectra.

並列關鍵字

gold nanoparticles ； titanium dioxide nanoparticles

參考文獻

(120) Huang, C.-C.; Huang, Y.-F.; Cao, Z.; Tan, W.; Chang, H.-T. Anal. Chem. 2005, 77, 5735–5741.

(6) Huang, C.-C; Huang, Y.-F.; Cao, Z.; Tan, W.; Chang, H.-T. Anal. Chem. 2005, 77, 5735–5741.

(12) Huang, T.; Murray, R. W. Langmuir 2002, 18, 7077–7081.

(32) Lin, H.-Y.; Chen, C.-T.; Chen, Y.-C. Anal. Chem. 2006, 78, 6873–6878.

(56) Chen, S.-H.; Chang, H.-T. J. Chromatogr. A 2002, 966, 195–203.