- 學位論文
Surface Modification by Electrodeposition of ZnO Nanorods as Electrochemical DNA Biosensors
Surface Modification by Electrodeposition of ZnO Nanorods as Electrochemical DNA Biosensors
摘要
近年來有關DNA電化學生物感測器研究受到研究專家們熱烈的討論，由於感測器本身的高敏感度、精確性、簡單的設計、尺寸大小、低成本和低耗能。本次研究是利用氧化鋅奈米柱陣列表面固定化DNA偵測DNA的互補鹼基對。首先，氧化鋅(ZnO)奈米柱陣列藉由在玻璃表面以電沉積 的方式塗佈上銦錫氧化物，接者，探討最佳的電沉積 時間以及氯氣鋅(ZnCl2)與氯化鉀(KCl)的濃度，以提供高密度、大面積的氧化鋅奈米柱陣列。一般來說，氧化鋅奈米柱陣列的密度、分佈情形和尺寸大小與增加電沉積時間、氯化鋅和氯化鉀含量成正比關係，結果顯示在2.5mM氯化鋅、0.5mM氯化鉀和20mM過氧化氫透過反應時間25分鐘，獲得的氧化鋅奈米柱陣列有最高的密度，最後再利用3-環氧丙氧丙基（dimethylethoxysilane）當成交聯劑將固定DNA於表面，並且用循環電壓的方式評估感測器鐵氰化鉀(K3Fe(CN)6) 的變化，從氧化鋅奈米柱陣列循環電壓圖當中，可以看出氧化鋅奈米柱陣列循具有快速的電子轉移Fe(CN)64-/3- ，此外，氧化鋅奈米柱陣列相較於Das [42] 的納米結構氧化鋅薄膜，有更高的密度以及更大的表面積，能夠提供更佳的電導率。高密度ZnO和合成的DNA-ZnO/ITO生物感測器對於互補的鹼基對有極佳的偵測性和靈敏度，定量之偵測濃度可達10-9M 到 10-6M之間。
並列摘要
Recently, electrochemical DNA biosensors have received particular interest due to their advantages such as sensitivity, selectivity, accurate, simple design, small dimension, inexpensive platforms, and low power requirements. In this thesis, electrochemical DNA biosensors were developed by immobilizing probe DNA onto zinc oxide (ZnO) nanorod surface to detect its complementary sequence. ZnO nanorods were fabricated onto indium-tin-oxide (ITO) coated glass plate by electrodeposition. A survey of electrodeposition parameters including electrodeposition time, ZnCl2 and KCl concentrations was carried out in order to find a good experimental condition which supply a high density and large surface area nanorods as well as fully cover the deposited ITO plane. Generally, the density, distribution, and dimension of ZnO nanorods are more stable and increase with the gain of electrodeposition time, ZnCl2 and KCl content. The results indicated that the electrodeposition acchieved in the solution containing 2.5mM ZnCl2, 0.5mM KCl, 20mM H2O2 in 25 minutes would let the ZnO nanorods grow with extremely high density, next to each other and cover all the survey area of the surface. This parameter was chosen to fabricate ZnO nanorods for electrochemical DNA biosensors. After that, (3 – glycidoxypropyl) dimethylethoxysilane was attached with ZnO nanorods as a linker to immobilize probe DNA. Cyclic voltammetry was employed to evaluate the sensors’ electrochemical properties with assistance of potassium ferricyanide (K3Fe(CN)6) as an electrochemical indicator. Cyclic voltammograms of the sensors revealed that ZnO nanorods had fast electron transfer kinetics with Fe(CN)64-/3- redox couple. The peak current values of our ZnO nanorods are higher in comparison with those of Das et al. ‘s nanostructured ZnO films due to their higher density and larger surface area, suggesting that the developed ZnO nanorods exhibited greater conductivity. The electrochemical response of the DNA–nsZnO/ITO bioelectrodes has also been investigated as a function of complementary target DNA concentration from 10-9M to 10-6M. The results uncovered that DNA-nanorod ZnO/ITO biosensors possesed great detectivity and sensivity due to high density and large surface area of synthesized ZnO nanorods.