探討逐步調控氧化石墨烯之含氧官能基於電化學表面電漿子共振技術增強免疫感測晶片靈敏度之應用

Abstract

本研究利用電化學表面電漿子技術(Electorchemical surface plasmon resonanc, EC-SPR)進行氧化石墨烯(Graphene Oxide, GO)還原。透過SPR即時監測其還原過程，藉由偵測金屬-介電質之間表面折射率的變化與SPR角位移的改變，判斷氧化石墨烯的還原狀況。將電化學還原後的還原氧化石墨烯(Electrochemical Reduce Graphene Oxide, ERGO)進行阻抗分析，觀察其還原後的導電特性。並將此薄膜作為生物蛋白分子檢測薄膜，分析其檢測靈敏性。 本實驗採用兩種不同電化學還原技術進行GO的還原與比較，分別為循環伏安法(cyclic voltammetry, CV)與定電位還原法(Constant voltage)。在不同還原條件的ERGO薄膜，將使用電化學阻抗譜(Electrochemistry Impedance Spectroscopym, EIS)、X射線光電子能譜(X-ray photoelectron spectroscopy, XPS)以及傅立葉轉換紅外光譜(Fourier-Transform Infrared Spectrometer, FTIR)進行分析。 分析的結果顯示，利用電化學表面電漿子技術可以即時監測與逐步控制GO的碳氧比。還原後的ERGO薄膜，其氧官能基比例大幅的下降。使用恆定電位還原120秒之ERGO，其碳氧比由3.97增加至71.46，阻抗值也大比例下降，大幅度提升其導電性。 在生物感測方面，將牛血清蛋白(Bovine Serum Albumin, BSA)修飾於薄膜，並注入不同濃度的Anti-BSA進行阻抗分析，其偵測極限濃度可達到100 pg/ml的高靈敏性。而恆定電位還原法120秒的ERGO薄膜，其Anti-BSA的阻抗響應高於循環伏安法還原100圈的ERGO薄膜約兩倍。

In this study, we use the electrochemical surface plasmon resonance (EC-SPR) to detect the reduction process of Graphene Oxide (GO) in real time. EC-SPR is capable for detect the changes of refractive index near the surface and SPR angular displacement of dielectric-metal interface. The reduction status of GO converted to electrochemical reduce graphene oxide (ERGO). After reductive process, the ERGO film acts as a bio-detection thin film, and we will analyze its detection sensitivity. In this experiment, we use two different electrochemical process to reduce the GO. One of them is Cyclic Voltammetry (CV) and the other is Constant Voltage (it-curve). In the different reductive conditions of ERGO film, we will analyze material properties by electrochemistry impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectrometer (FTIR). Analysis results demonstrate that the EC-SPR can quantitatively detect in real time and tune the C/O ratio of GO. The proportion of oxygen functional groups is dropped significantly by these two process. In constant potential reductive process, the C/O ratio is turn from 4.93 into 72.88 after 120 seconds, and the impedance is dropped about 37 times to increase the electrical conductivity. As a high sensitivity bovine serum albumin (BSA) detection thin film, we inject the different concentrations of Anti-BSA to analyze by EIS technology and the limit of detection (LOD) is 100 pg / ml. The impedance response sensitivity of the constant voltage corresponding to 120 s of ERGO towards Anti-BSA is about 2 fold higher than that of the cyclic voltammetry corresponding to 100 cycles of ERGO.