Poly-Si Film Type Nanowire DNA Biosensor with γ-APTES/Nanoparticles Nanocomposite Sensing Membrane

[[abstract]] 本篇論文主要研究利用多晶矽薄膜型奈米線(Poly-Si Film Type Nanowire, FTNW)來檢測DNA，為了要控制操作電流的範圍，我們設計一個寬為100 nm側邊具備大面積的感測區的多晶矽薄膜型奈米線之圖案。本實驗利用溶液相沉積法(Solution phase deposition) 使用3-氨基丙基三乙氧基矽氧烷(γ-APTES)與二氧化矽奈米顆粒(γ-APTES +NPs)混成複合材料，並在多晶矽表面上形成感測膜，再以戊二醛修飾表面後嫁接不同類型的合成DNA。我們研究以合成單股DNA ，如poly-adenine [poly(A)]﹐poly-cytosine [poly(C)]﹐poly- guanine [poly(G)]﹐poly- thymine [poly(T)]與改質薄膜表面進行反應，並以紫外光/可見光光譜儀量測，分析DNA的長度、濃度以及嫁接時間之吸收峰值的趨勢變化。在紫外光/可見光光譜中我們觀察到吸收峰與DNA濃度之間有好的線性關係，因此我們可以合理的猜想經表面改性的戊二醛分子成功地與各種合成的DNA結合。 多晶矽薄膜型奈米線(FTNW)感測DNA的電流量測結果顯示，固定鹼基的數量及不同類型的單鏈DNA在多晶矽薄膜型奈米線(FTNW)上的電流變化大小為poly(T)> poly(C)> poly(G)> poly(A)，且DNA的濃度和長度的電流變化呈線性增加，顯示多晶矽薄膜型奈米線(FTNW)作為DNA生物感測器的有效性性。我們發現DNA生物感測器利用表面奈米顆粒改質可大幅增加DNA感測範圍。其中poly(A)可偵測範圍10-10 M~10-5 M改善至10-18 M~10-5 M，最低偵測極限改善8個數量級；poly(C) 可偵測範圍10-15 M~10-5 M改善至10-18 M~10-5 M，最低偵測極限改善3個數量級；poly(G) 可偵測範圍10-15 M~10-5 M改善至10-18M~10-5 M，最低偵測極限改善3個數量級；poly(T) 可偵測範圍10-16 M~10-5 M改善至10-18 M~10-5 M，最低偵測極限改善2個數量級。大部分的電流變化與DNA濃度曲線表現三個線性區域，我們利用化學反應限制與擴散限制模型解釋這個現象。 與傳統的半導體製程相容，多晶矽薄膜型奈米線(FTNW)因具有大面積的側邊感測區域，使用γ-APTES +NPs和戊二醛改質表面，元件能表現出良好的性能，因此可作為一個合適的無標記DNA檢測元件。 [[abstract]]In this thesis, we investigated the DNA sensing performance of poly-Si film type nanowire (FTNW). The width of poly-Si FTNW is only 100 nm but having a large side sensing area. The configuration of the poly-Si FTNW was specifically designed in pattern with an operation current range suitable for DNA detection. The poly-Si surface was coated with γ-APTES and silica nanoparticles nanocomposite growing by solution phase deposition followed with glutaraldehyde modification for grating different types of DNA strains. Synthetic DNA including the single-strained (ss)-homopolymers poly-adenine [poly(A)], poly-thymine [poly-(T)], poly-cytosine [poly(C)], and poly-guanines [poly(G)] were grafted on modified surface as identified by UV/visible spectrometer. The relationships between absorption peak and DNA length, concentration as well as grafting time were analyzed. Good linear relationships between the UV-vis main absorption peak and DNA concentration were observed. It was a reasonable conjecture that the glutaraldehyde molecule on modified surface successfully bonded with all types of synthetic DNA. Characterization of DNA by channel current modulation of FTNW with silica nanoparticles nanocomposite for surface modification showed that, for a fixed number of bases, influence of different types of single-strained DNA on channel current modulation of FTNW was poly (T) > poly (C) > poly (G) > poly (A). The current changes increased linearly with concentration and length of DNA, showing that the effectiveness of the poly-Si FTNW for used as a DNA biosensor. We found that poly-Si FTNW DNA biosensor using the nanoparticles for surface modification could significantly improve the detection range of DNA. The detectable range of poly (A) was improved from 10-10 M ~10-5 M to 10-18 M ~10-5 M, and the lowest detection limit was improved by 8 orders of magnitude; The detectable range of poly (C) was improved from 10-15 M ~ 10-5 M to 10-18 M ~ 10-5 M, and the lowest detection limit was improved by 3 orders of magnitude; The detectable range of poly (G) was improved from 10-15 M ~ 10-5 M to 10-18 M ~ 10-5 M, and the lowest detection limit was improved by 3 orders of magnitude; The detectable range of poly (T) was improved from 10-16 M ~ 10-5 M, and the lowest detection limit was improved by 2 orders of magnitude. Most of the curves showed three linear regions in the detectable range. Reaction-limited and diffusion-limited models were used to qualitatively explain this phenomenon. Compatible with the conventional semiconductor process, the poly-Si FTNW with a large side sensing area, using the γ-APTES+NPs and glutaraldehyde for surface modifications showed good performance as a label-free DNA detection device.[[note]]碩