Using Polysilicon Wire Sensor for Sequence-Specific Label-Free DNA Detection

[[abstract]] 本論文在探討利用多晶矽線為基礎發展偵測特定序列去氧核醣核酸 (Deoxyribonucleic acid, DNA) 序列之半導體生化感測器，在本實驗中，將單股的DNA序列Adenine (A)、 Thymine (T)、 Cytosine (C)、 Guanine (G) 與雙股DNA序列ds (A-T)、ds (C-G) 滴於多晶矽線的元件表面上，並藉由電壓-電流特性曲線的分析，比較不同濃度與不同長度之特定序列之DNA所呈現出來的物理現象。 在製程方面，使用類似Silicon- on- Insulator (SOI) 的晶片來製作轉阻體。利用垂直爐管將多晶矽沉積於熱氧化層上，透過電子束微影的製程，直接在多晶矽薄膜上定義多晶矽線的結構後，再進行乾式蝕刻，將多晶矽線結構蝕刻出來。之後，將製作出來的多晶矽線經過表面化學處理藉以量測特定序列之DNA。 在本研究中，提供了一種量測特定序列DNA之研究方法，量測了不同長度與不同濃度的DNA序列，分別是長度為10-mer與20-mer的DNA序列，與濃度分別為100 nM與50 nM的DNA序列，從實驗結果當中證明了單股的DNA序列，依據電流值的大小依序均為Thymine (T)、 Guanine (G)、 Adenine (A)、 Cytosine (C)。 此外，在本實驗中也量測了不同長度與不同濃度的雙股DNA序列ds (A-T)、ds (C-G)，分別是長度為10-mer與20-mer的DNA序列，與濃度分別為50 nM與100 nM的DNA序列，在這實驗結果當中證明了雙股的DNA序列，依據電流值的大小為 ds (A-T) > ds (C-G)。 本論文提出以多晶矽線為基礎之無標定特定序列去氧核醣核酸生化感測器，以電流-電壓特性觀察其DNA序列所呈現出DNA序列之帶電荷的特性，有別以往利用螢光標定PCR的量測方式，避免了傳統利用螢光標定分析的過程中螢光分子對DNA之影響，以電性分析的方法呈現出DNA之物理特性。[[abstract]] In this thesis, we proposed a biochemical biosensor based on poly-silicon (poly-Si) wire for Sequence-Specific DNA detection. The advantage of using poly-Si wire as a biochemical sensor is that it provides a way of accurate biomedical molecular detection without adding any label, which eliminates the possible measurement interference from the label molecules. In this work, a trace amount of Sequence-Specific DNA solution to be tested was carried and dropped onto the poly-Si wire surface with the help of a capillary atomic force microscopy (CAFM) tip which was fabricated through the method of ion milling by using the focus ion beam technique. Single-strained DNA sequences Adenine (A), Thymine (T), Cytosine (C) and Guanine (G) as well as double-strand DNA sequences ds (A-T) and ds (C-G) were dropped onto the poly-Si wire surface with different lengths and concentrations and the current flowing through the poly-Si wire channel was measured. The current difference?I was then determined after and before the dropping of the tested DNA solution. It is found that the amount change of ?I for fixed length and fixed amount of concentration of single-strained DNAs was T > G > A > C. We also noticed that the ?I increases with increasing DNA length as well as concentration for both the single- and double-strained DNA sequences. It is found that the ?I for double-strained DNA is always higher than the corresponding single-strained DNA. For double-strained DNA sequence, we also observed that ds (A-T) has higher ?I than ds (C-G). From our experimental data, we confirmed that poly-Si wire can be used for the DNA sequence detection.[[note]]碩