電位調控下之脂質雙分子層電化學特徵分析

Abstract

本研究利用 Langmuir– Blodgett 技術與自組裝單分子層（SAM）修飾金基板，建立了高穩定性的 tethered bilayer lipid membrane (tBLM) 仿生膜模型，並結合電化學阻抗譜 (EIS) 分析脂質雙分子層在不同電位下的動態響應。我們透過控制單層壓縮表面壓力，成功製備出高密度與低密度的雙分子層模型，並發現其結構鬆緊與含水量差異會顯著影響離子滲透行為。實驗結果顯示，脂質雙層在正偏壓下維持高度絕緣性，低頻響應主要由界面電雙層充電主導；然而在負偏壓下，膜電阻呈現數量級下降，並伴隨特徵頻率向高頻偏移，顯示離子能更容易穿透膜結構。此一正負偏壓的不對稱性揭示了跨膜導通的方向性特徵，並指出雙層膜水合作用在決定其電化學性質中扮演關鍵角色。本研究提供了一個連結理論與活細胞層級的實驗平台，可進一步應用於藥物遞送、膜蛋白功能研究及電穿孔相關生物醫學技術。

In this study, we used the Langmuir–Blodgett trough together with self-assembled monolayer (SAM) modified gold substrates to build a stable tethered bilayer lipid membrane (tBLM) model, and combined it with electrochemical impedance spectroscopy (EIS) to analyze the dynamic response of lipid bilayers under different applied potentials. By controlling the monolayer compression surface pressure, we prepared high-density and low-density bilayer models and found that differences in packing and hydration strongly affect ionic permeation. The measurements show that under positive bias, the bilayer remains highly insulating, with the low-frequency response dominated by interfacial double-layer charging; in contrast, under negative bias, the membrane resistance drops by orders of magnitude and the characteristic frequency shifts to higher values, indicating that ions more readily penetrate the membrane. This asymmetry between positive and negative bias reveals the directional nature of transmembrane conduction and underscores the key role of bilayer hydration in determining electrochemical properties. Overall, the approach provides an experimental platform that bridges theoretical descriptions with questions at the live-cell scale, and can be extended to studies of drug delivery, membrane protein function, and electroporation-based biomedical techniques.