DNA配對光學量測理論及實驗

Abstract

本論文欲建立一光學折射率之量測理論模式，並設計一實際量測之實驗，用以偵測DNA於溶液中之配對情況。在考量一般現有的生物晶片之設計後，我們決定使用一多層膜之結構，其中膜的厚度及排列方式各有不同組合，受測之試樣為其中之一層，將光源入射到此結構，依照各層光學性質的不同，經過多重反射之傳輸過程後，會產生部分反射、部分穿透和部分吸收的效果，當膜的厚度小到某一程度後，干涉效應應被考慮。我們首先推導出多層膜結構之光學反射率及穿透率的公式，用來描述光在不同的光學折射率及厚度的情形下，能量傳輸的結果，再利用最小平方誤差法，來進行光學折射率之逆運算分析。我們將探討不同參數變化對於光反射及光穿透之影響，以期在逆運算分析時，能取得最佳的實驗量測組合。在實驗的部分，我們利用建立的量測理論，偵測含有DNA樣品之試液在不同的濃度及配對程度下之光學折射率，並探討此方法在生物分子定量量測之應用性。關於DNA配對過程中雙鏈DNA之解離，我們採取熱學方式來加以控制。

This thesis purposes to develop an optical transduction for detection of DNA hybridization. After considering existing biosensors, the physical model adopted is a multi-layer structure for the present study. The arrangement of layer sequences and thicknesses might be random, and the testing sample layer is included. Due to various optical properties of layers, there exist different degrees of reflection, transmission and absorption of electromagnetic energy with multiple reflections inside the multi-layer structure. Interference effect should be considered as the layer thickness is small. We firstly derive the expressions for reflectance and transmittance of the multi-layer structure, which describe the energy transport under different combination of optical properties and thicknesses of layers. For inverse estimation of optical properties of a specific layer in the structure, the least squared error method is then utilized. Results of the inverse analysis should lead to an optimal design for the experimental measurements. The optical properties of DNA fragment solution in different degrees of hybridization are then measured in association with above-mentioned analysis. As to the controlling of DNA hybridization degrees, the thermal denaturation is utilized.