濃度梯度對塗佈電荷可調節之聚電解質的錐狀奈米孔道中離子傳輸行為之影響

Abstract

受到生物細胞膜上離子通道的啟發，合成奈米孔道成為近年來相當熱門的研究領域之一，相關課題之討論廣受學者重視，其中特別是具有表面改質之錐狀奈米孔道。這是因為它具有離子選擇性與離子電流整流效應，並已廣泛應用於DNA序鏈檢定或作為生物感測器。為了能貼近真實生物膜上孔道中的離子傳輸情形，吾人考慮一圓錐狀之合成奈米孔道，其表面塗佈一層pH可調節之聚電解質，於孔道兩開口端連接兩大小相等之電解池。吾人結合Poisson-Nernst-Planck方程式與Navier-Stokes方程式，在電場與濃度梯度同時施加下考慮電動滲透流對離子選擇性與離子電流整流效應的影響，其中特別探討了濃度梯度方向的影響，也完整地探討不同pH下的相關效應。本文所獲結果除可供具有表面改值之合成奈米孔道設計之參考外，亦可為實驗者於實驗設計中參數調整之依據。

Due to its capability of mimicking the ion channels on the living cell membrane, synthetic nanochannels become an important model system for relevant research topics recently. Issues associated with them have drawn the attention of researches in various fields. Among various types of nanochannel, synthetic conical nanopores with surface modification are of particular interest due to their ion selectivity and ionic current rectification (ICR) behaviors. This type of nanopore has been applied successfully in DNA sequencing and biosensors. To mimic more realistically the ion transport in the ion channel of living cells more, we consider a synthetic conical nanopore with its surface modified by pH-tunable polyelectrolyte (PE) brushes connecting two identical large reservoirs. We solve simultaneously the Poisson-Nernst- Plank equation and Navier-Stokes equation, and the results adopted to examine the influence of the electrokinetic flow(EKF) on the ion selectivity and ionic current rectification for the case where both an electric field and a salt gradient are applied. The direction of the applied salt gradient and the level of pH are investigated for their influences on the behavior of the nanochannel. The results gathered in this study provide valuable information for designing synthetic nanopore devices as well as adjusting the values of key parameters.