微晶片電泳高分子基材之電滲流性質探討

Abstract

近年來高分子微晶片電泳因其成本低廉製作簡單，於各類應用上發展出相當多的基材。本研究則以最常見之PMMA(壓克力)及PDMS(聚二甲基矽氧烷)為對象，分別採用熱壓法與矽模板輔助之灌注成型法製作所需的微流道。實驗中探討緩衝溶液酸鹼值、修飾劑、樣品注射時間或體積、流道線寬、外加電場等因子，對晶片表面特性及分析情形之影響。其中，為了改善高分子流道表面的疏水性質及調控適當的電滲流，以動態塗佈(添加界面活性劑)及電漿處理對管壁進行修飾。 結果呈現當緩衝溶液內含有陰離子型介面活性劑(SDS)時，不僅具有穩定電滲流的作用，也增加螢光試劑的放射強度。結合雷射誘發偵測法與本實驗室自行設計製作之晶片固定座夾具，可成功達到快速分離螢光黃異硫氰酸酯(FITC)及螢光素(Fluorescein)這兩種測試分析物。最後應用於分析經FITC螢光試劑衍生後的胺基酸產物，以添加含有2 mM SDS的10 mM pH 8.2 Borate緩衝溶液，在施加電場強度為200 V/cm下，於200秒內能有效分離精胺酸(Arginine, Arg)、甘胺酸(Glycine, Gly)、天冬胺酸(Aspartic acid, Arg)三種分析物。

Recently, polymer-based microchip electrophoresis has been developed with low-cost, simplified fabrication procedure and a wide range of available materials for specific applications. Two popular materials for microchips, polymethyl methacrylate (acrylic) and polydimethylsiloxane (PDMS) are used in this study. Plastic microchannels were fabricated by imprinting or casting with silicon template. For characterizing the surface properties and analysis conditions, the effects of pH value of buffer, modifier, injection time or volume, the width of channels, and applied field were demonstrated. In order to improve the hydrophobicility of surface and control the magnitude of the electroosmotic flow (EOF), we modified the wall by dynamic coating (addition of surfactant) and treated with oxygen plasma. The experimental data showed that when negatively charged surfactants (SDS) in the background buffers, they could stabilized run-to-run EOF and enhanced the intensity of fluorescent dyes. Combing with laser-induced fluorescence detection and laboratory-built chip holders, high-speed separation of Fluorescein isothiocyanate (FITC) and Fluorescein were successfully achieved. Finally, the approach was applied to the analysis of FITC-labeled amino acids. Under optimized conditions, efficient separation of Arg, Gly, Asp was obtained within 200 s at 200 V/cm.