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標題: | 帶電高分子通過微孔洞行為之研究 Electrophoresis of a Charged Polymer in a Nanopore |
作者: | Li-Wei Yu 余立偉 |
指導教授: | 諶玉真(Yu-Jane Sheng) |
關鍵字: | 微孔洞,帶電高分子,電泳, nanopore,charged polymer,electrophoresis, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 在本文的研究中我們利用了布朗動力學(Brownian Dynamics)法來模擬帶電高分子的電泳運動行為,其研究方向主要分為兩個部分:第一部分是利用DNA在具有孔洞且加入鹽類離子水溶液的系統,在施加電場進行電泳時,DNA在通過孔洞的過程中會阻礙鹽類離子的移動,藉由偵測阻礙電流的方式,來分析DNA的結構與長度;第二部分則是模擬帶電高分子在油滴底下窄通道內的運動行為,藉由模擬的方法來解釋實驗中所觀察到的現象。
我們在第一部分的研究當中,針對不同的帶電高分子的結構、長度以及鹽類離子濃度模擬,從模擬的結果發現上述這三個因素會明顯的影響到阻礙電流以及阻礙時間。在固定長度的情況下,圈狀的帶電高分子阻礙電流會大於線性高分子,且長度越長的帶電高分子的阻礙時間也會隨之增加,除此之外鹽類離子濃度增加,阻礙電流明顯加大;第二部分我們模擬油滴下方帶電高分子的運動情形,在模擬過程中我們發現在電場梯度大的時候,長、短鏈段的帶電高分子皆易被拉伸,但隨著電場梯度降低,短鏈段的帶電高分子由於電場作用力變小的關係,亂度的重要性增加,故不會呈現被拉伸的狀態。而較長鏈段的帶電高分子由於電場的作用大於亂度的效應,故會較易被拉伸。不同長度的帶電高分子具有不同的臨界電場梯度,也符合實驗中所觀察到的現象。 在這一系列的研究中我們利用布朗動力學法,可以確切的觀察帶電高分子的長度、形狀以及鹽類離子濃度對阻礙電流的影響,並藉由觀察帶電高分子實際運動的軌跡以及如何阻礙鹽類離子的移動,除了和實驗的文獻比對外並可以提出實驗所觀察不到的現象。而另一部分模擬帶電高分子在油滴底下運動的情形,我們提出了電場梯度的概念,也成功地解釋了實驗所作出的現象。 A DNA molecule’s conformation and configuration as well as its number of bases and sequence are important characteristics that affects its functional properties. A simple method that can simultaneously determine DNA conformation and base number would be advantageous. Fologea and his coworkers proposed a method in which a nucleic acid polymer translocates through a pore in a voltage biased silicon nitride membrane. The ionic conductivity is partially blocked. Analyses of blockage amplitudes and blockage durations can reveal information about polymer length and conformation. In this work, Brown Dynamics was used to study the behavior of polyelectrolytes electrophoresed through a nanopore. It was found that the measured time integral of blocked ionic current, also known as the event-charge-deficit, ecd, for each translocation event was the same regardless of whether the molecules were in a linear or circular form. However, when polyelectrolytes containing different number of monomers were electrophoresed through a nanopore, the ecd depended strongly on the total length. Simulation results also showed that the magnitude of the current blockages was strongly affected by a molecule’s form. Circular polyelectrolytes blocked more ionic currents than linear ones did. Yet, the blockage duration times of circular polyelectrolytes were consistently shorter than those of the linear ones with identical chain length. Our simulation confirmed that it is possible to simultaneously determine both DNA conformation and base number by using a single nanopore assay. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/40984 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學工程學系 |
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