氧化鋁電容式電極於免疫球蛋白G抗體偵測研究

Abstract

本研究主要探討氧化鋁電容式電極最佳化的修飾條件及生醫感測應用。首先使用汽相蒸鍍方式自我組裝裝分子層APTMS在電極表面上，再用戊二醛架橋連接APTMS與一抗Mouse IgG，之後利用免疫反應專一性鍵結二抗 Anti-mouse IgG，透過螢光的變化量來驗證，使用汽相蒸鍍APTMS在氧化鋁電容式電極的效果比液相修飾好，另外、抗體在電極表面的修飾狀況和選擇性相較於二氧化矽都有較佳的結果。我們以循環伏安法量測各層修飾分子造成的電容式電極電容變化，隨著修飾多層分子，電極電容隨之下降。此外，我們將電容式電極連接電晶體，架設成電容式延伸閘極電晶體，使用半導體分析儀HP4284，量測電容-電壓圖形的位移狀況，在加入不同濃度的Anti-mouse IgG後，因為Anti-mouse IgG帶負電，電容-電壓圖形往正電的方向位移，以分辨出六個等級的變化量 (100 μg /ml~1ng/ml)，在最高與最低濃度，電位的改變量為22mV、85mV，偵測極限為1 ng/ml，比螢光可以辨識的範圍再低一個等級。從抗體Anti-mouse IgG標記的螢光亮度可以分辨出五個等級的變化量(100 μg/ml~10 ng/ml)。本實驗成功修飾抗體在氧化鋁電極上且具有選擇性，並初步使用電容式場效感測器與電容式延伸閘極電晶體測量到生物分子電容以及電位的變化，提供對於電容式電極和延伸式閘極系統量測有重大的幫助。

In this research, optimization of surface modification conditions of Al2O3 capacitive electrode for biomedical detection has been carried out. Self-Assembled Monolayer (SAM) of 3-aminopropyl- trimethoxysilane (APTMS) were modified on the Al2O3 capacitive electrode by thermal evaporation, then Glutaraldehyde molecule acted as cross-linker to connect APTMS and Mouse IgG, and finally Anti-mouse IgG selectively bond to Mouse IgG. Fluorescence was adopted to characterize the surface modification and proved that deposition APTMS on Al2O3 capacitive electrode by thermal evaporation were better than that in liquid phase. The intensity of fluorescence as a result of Ab-Ag binding can distinguish 5-order of Ag concentrations (100 μg/ml ~ 10 ng/ml). We use Cyclic voltammetry (CV) to measure the capacitance change cause by modified molecular. CV results showed that capacitance decrease after the presence of each additional molecular layer. On the other hand, we connected capacitive electrode to the field-effect-transistor to function as a capacitive extended gate to field effect transistor and monitored Capacitance-Voltage curves using an impedance analyzer (HP 4284). Shift of Capacitance-Voltage curves to the positive direction as the presence of anionic Anti-mouse IgG. The potential shift can distinguish 6-order of different concentrations of Anti-mouse IgG(100 μg/ml ~ 1 ng/ml). The detection limits was 1 ng/ml which lower than that of fluorescence detection. The results of this research provide a model of capacitive extended gate field effect transistor in biosensing applications.