介電濕潤驅動包覆式微液滴建構水膠支撐非對稱脂質雙層膜

Abstract

本論文結合數位微流體操控及脂質分子自組裝形成脂質雙層膜的概念，以介電濕潤晶片驅動兩包覆式液滴使表面的兩層脂質單層接觸自發形成脂質雙層膜，改良發展多年之數位微流體成膜平台包括：(1)以透明ITO玻璃基材設計共平面電極取代原先以銅基材製作之指叉型共平面電極；(2)將原先以矽晶片製作成膜孔洞基材改為可由微影製程圖形化之乾膜光阻；(3)分別操控脂質單層組成互相獨立之兩包覆式液滴建立非對稱脂質雙層膜；(4)將光感型水膠PEG1000-DMA加入微液滴，並在脂質雙層膜形成後以長波段紫外光照射固化，作為支撐。於此建立之透明三明治結構成膜平台，共平面電極作用面積更大，能更有效的驅動包覆式液滴、容易進行光學觀察、僅需藉由光罩的設計即可定義成膜孔洞之形狀、大小，擁有更大的晶片設計自由度，提供脂質雙層膜更穩定的支撐邊界，而包覆式液滴油相的不連續性在形成非對稱脂質雙層膜上更具有相當大的優勢。水膠支撐則提高了脂質雙層膜對應力的承受度、減少因微液滴蒸發產生的位移，也間接固定插入液滴的銀─氯化銀電極因此減少雜訊發生率。我們成功於此平台建構對稱與非對稱脂質雙層膜，比較兩者電容值無明顯差異，與文獻相符，同時也建構了水膠支撐非對稱脂質雙層膜，電容值為33.27 pF，厚度為5.64 nm，以光學觀察記錄判斷穩定時間最長可達31分鐘。但微液滴的蒸發現象仍對脂質雙層膜及電生理量測造成很大的影響，因此未來建構穩定量測的全油環境成膜平台便成為首要目標。

In this thesis, bilayer lipid membranes (BLMs) is formed by two lipid monolayers self- assembled at the water/oil interfaces of two encapsulated droplets driven independently by electrowetting-on-dielectric (EWOD) on a digital microfluidic platform. Here several improvements of the platform are demonstrated, including using (1) Indium Tin Oxide (ITO) transparent coplanar electrodes, (2) photo-definable BLM aperture across PerMX sheets, (3) two encapsulated droplets containg different lipid solutions to form asymmetric BLMs, (4) photo-crosslinkable hydrogel PEG1000-DMA to support BLMs. In our sandwich-structure artificial BLMs platform, we effectively manipulated droplets and clearly provided an optical inspection through transparent coplanar electrodes. By using PerMX sheets, the shapes and dimensions of membrane were defined by photomasks, with flexible designs to provide a stable and durable suspended boundary for BLMs. Moreover, the discontinuous oil phase containing different lipid molecules, of the encapsulated droplets is advantageous to form asymmetric BLMs. Furthermore, by crosslinking the encapsulated droplets having hydrogel prepolymers, the BLMs and Ag/AgCl electrodes were better supported with reduced droplet movements in evaporation. Symmetric BLMs and asymmetric BLMs were successfully formed with similar measured BLM capacitances. The capacitance, thickness and life time of an asymmetric BLM supported by hydrogel were about 31 min, 33.23 pF, 5.64 nm and respertiely, we observed that vaporation of droplets inference BLMs and electrophysiology measurement significantly. Reducing droplet evaporation with a filler oil medium would be one of ther future goals to study membrane protein on the reported platform.