拉曼散射是一種強而有力的分析技術，它能提供分子結構上的資訊並應用於快速的篩檢或是分子蹤跡的檢測上。然而，在實際檢測上，環境中的背景值將會模糊掉實際待測的拉曼訊號。因此，在幾年來，如何發展出一個簡單的檢測樣品前處理技術並應用於實際的分子蹤跡檢測上已經成了研究的顯學。在這個新興的領域當中，最常見的方法就是在檢測基板上結合液相層析方法與表面增強拉曼光譜技術，達到高信躁比的量測。

　　在本論文中，我們提出了一個全新的液相層析/表面增強拉曼光譜技術結合的檢測基板。此基板是透過濕式蝕刻製程製備而成的銀奈米顆粒鑲嵌於矽奈米線陣列結構，在此論文中我們將以Ag@SiNWs通稱之。此Ag@SiNWs結構中富含豐富的銀顆粒，透過表面電漿子共振的方式能在特定區域形成電磁訊號增強的熱點，提升待測物拉曼訊號的強度。

　　此外，結合液相層析法，能藉由混合樣品中各別分子對檢測基板與移動溶劑的極性差異，進行拉曼待測分子與混合物的分離，進而大幅提升其量測的信躁比。在此部分，我們將有顏色的染料混合物作為待測物，經液相層析後，在基板上形成許多不連續的顏色線條。透過此顏色的分布，驗證了分離的概念。此外，從拉曼線性掃描光譜中，我們也可以觀察到每個染料分子出現在不同的基板位置上。
透過三聚氰胺從牛奶中分離的實驗，我們證實了此基板能應用於實際的檢測上。
在液相層析作用後，三聚氰胺的分子將會出現在離一開始混合液滴定點幾毫米的地方。此外，我們也可以觀察到非常強的三聚氰胺訊號峰值源自於在雷射光點下牛奶分子的消失以及三聚氰胺分子本身的聚集。

　　從分析物噴灑區域的研究當中發現到，結合液相層析發法發應用於拉曼待測分子的檢測不僅能提供更少的背景值干擾，也能解決液體在移轉到基板上所遭遇的點樣問題。再者，由於此基板的基底是由矽所組成，當中的矽的拉曼峰值也能當作是拉曼光譜的內建標定值，透過此知道在特定區域的表面電漿子共振增強程度。

　　有著低成本製程、高信躁的檢測、拉曼內標等特性，我們相信此基板能有潛力應用於實際的生化快篩檢測上。

Raman scattering is a powerful analytical technique that reveals structural information of molecules to provide fast screening and trace detection applications. However, in practical detection, background signal from environments will blur the signals from real Raman targets. Therefore, developing a simple pre-treatment method for trace analyte detection in practice becomes a research focus in recent years. In this new research region, a common method is to couple traditional liquid chromatography (LC) technique with surface-enhanced Raman spectroscopy (SERS) on a chip for high signal-to-noise (S/N) ratio detection.

　　Here, we propose a new LC/SERS substrate that is comprised of a silicon nanowire array decorated with silver particles fabricated by a simple chemical wet etching process and hereafter is denominated as Ag@SiNWs in this dissertation. Such Ag@SiNWs could provide abundant electromagnetic hot spots among silver nanoparticles to enhance target’s Raman signal via localized surface plasmon resonance (LSPR).

　　Furthermore, by employing chromatography, a mixture of targets and other ingredients can be separated due to different molecular polarities toward the substrate and mobile solvent to dramatically increase the corresponding S/N ratio in Raman spectrum. In this part, we visually demonstrate the concept of separation in a colorful dye mixture with discrete color lines on the substrate. Also, from Raman line-scan spectrum, we observe the separation since each dye spectrum appears in different locations. In practical demonstration, we validate the concept of separation by extracting melamine from milk. After chromatography development, the location of melamine appears at several mini-meter far from original mixture spraying point. Besides, an incredible strong peak of melamine is also observed due to the disappearance of milk in laser beam spot area and melamine molecular concentration.

　　From the study of analyte spraying region, it is believed that coupling with chromatography technique on ramnan targets detection can not only provide
less background noise from other molecules but also solve the spotting issue suffered in droplet transfer process. Further, since the substrate is fabricated from Si wafer, the existence of Si peak can also behaves as a inner marker in Raman spectrum to know the LSPR enhancement in defined area. With such low-cost fabrication , high S/N ratio detection, Raman inner marker (Si) property, we believe this substrate poses the potential for real world bio-chemical rapid screening use.

摘要………………………………………………………………………………....… I
Abstract……………………………………………………………………………..... II
Acknowledgements……………………………………………………………..……IV
Content………………………………………………………………………………..V
List of Figures……….………………………………………………………………VII
List of Tables……………………………………………………………………..…XV
Chapter 1 Introduction………………………………………………………………...1
Chapter 2 Literature review……………………………………………………………3
　　2.1 Surfaced-enhanced Raman spectroscopy (SERS) …………………………...3
　　　2.1.1 Raman technique………………………………………………………...3
　　　2.1.2 Surface-enhanced Raman spectroscopy…………………………………5
　　　2.1.3 Plasmonic paper…………………………………………………………9
　　2.2 Thin layer chromatography (TLC)……………………….…………………11
　　　2.2.1 Planar chromatography…………………….…………………………...11
　　　2.2.2 Evolution of the stationary phase……………………………………....15
　　　2.2.3 Ultra-thin layer chromatography……………………………………….16
　　2.3 Combination of TLC and SERS…………………………………………….26
　　2.4 Motivation…………………………………………………………………..31
Chapter 3 Design of Experiment……………………………………………………..33
　　3.1 UTLC substrate fabrication procedure……………………………………...33
　　　3.1.1 Metal associated with chemical etching (MaCE)………………………33
　　　3.1.2 Silver (Ag) reduction reaction………………………………………….36
　　3.2 Chromatography separation……………………………………...…………39
　　　3.2.1 Analyte preparation…..……………………………………...…………39
　　　3.2.2 Spotting technique…………………………………………...…………39
　　　3.2.3 Chromatography development…………………………………………44
　　3.3 Raman measurement……………………………………………….…….…46
Chapter 4 Result and discussion……………………………………………………..47
　　4.1 Benefit of Nanowire structure………………………………………………47
　　　4.1.1 Surface property --- Contact angle measurement………………………47
　　　4.1.2 Chromatography development comparison…………………………….49
　　　4.1.3 Raman measurement comparison………………………………………49
　　4.2 Dye separation………………………………………………………………51
　　　4.2.1 Appearance of Dye separation………………………………………….51
　　　4.2.2 Raman measurement result………………………………………….....52
　　4.3 Melamine milk mixture separation………………………………………….55
　　　4.3.1 Melamine milk sample pre-treatment…………………………………..55
　　　4.3.2 Melamine milk separation (50ppm, 30ppm , 5ppm)..………………….59
　　　4.3.3 Stationary phase study _ Length effect………………………………...61
　　　4.3.4 Mobile phase study_ Polarity effect……………………………………65
　　　4.3.5 Analyte concentration mechanism………………………………...……67
　　　4.3.6 Raman mapping measurement……………………………………...….68
　　4.4 Mobile phase Raman spectrum……………………………………………..73
Chapter 5 Conclusions ………………………………………………………………74
References……………………………………………………………………………76

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