電荷可調節粒子的電泳:邊界與粒子表面電荷分布的影響

Abstract

電泳是膠體科學領域中相當重要的電動力學現象之一，並於近年應用於像是生物感測、藥物傳遞、DNA定序等方面。 因此，為了要更進一步描述各種生物粒子的電泳行為，深入的行為分析是必須的。 在本論文中，我們採用了軟性粒子的假設，一種被廣泛採納，用以模擬各種生物型膠體粒子的模型。另外，為了更貼近於真實情況，我們假設此軟性粒子膜內具有電荷可調節的雙官能基，且此膜的帶電情況將隨其自身性質以及此時溶液的狀態而改變。 在此同時，相較於以往研究中典型的雙離子系統，我們採用了溶液中具有多種離子的系統，這是更貼近實際的。 針對此論文中膠體粒子的電泳行為，利用膜內官能機密度、背景電解質的濃度、以及膜厚的變化與邊界效應進行討論。 我們另外發現對於電荷可調節的粒子，其具有自發性地使表面的解離電荷分布不均的特性。除了對此提出解釋，更進一步探討這個現象對於電泳行為可能的影響。 最後，我們討論藉由改變背景電解液的種類，發現在某些條件之下其對於膠體粒子的電泳行為影響甚鉅。 本論文的結果除了對實驗中可能發生的現象提出了解釋，並提供了實驗研究學者設計、解釋、及參數設定時具參考價值的資訊。

Electrophoresis is one of the most important electrokinetic phenomena in the region of colloidal science and has been applied to small devices such as biosensors, drug delivery, and DNA sequencing recently. Therefore, a more thorough analysis to mimic the electrophoretic behaviors of biocolloids is necessary. In this study, the assumption of soft particle is adopted, which is widely used to simulate the behaviors of bio-particles. In addition, we assume the porous layer is charge-regulated and the liquid phase of the system contains multiple ionic species, making the problem considered here is closer to reality. Focusing on the electrophoretic behavior of this study, boundary effect, variations of the functional groups density, background concentration, and the thickness of membrane are utilized to discuss. We also discover the nature of self-induced nonuniform surface charge density for a zwitterionic particle, the influences of the nonuniform charge density and the types of background electrolyte are discussed. This research not only provides reasonable explanations behind special observation in experiments but possibly predicts extraordinary phenomena in future studies.