體溫環境對葡萄糖感測器選擇性半透膜之感測影響

Sensing performance of perm-selective membranes of glucose biosensors in a simulated body temperature environment

蔡昌憲(Chang-Hsien Tsai)

指導教授 ： 婁世亮

中原大學/工學院/醫學工程研究所/碩士(2009年)

https://doi.org/10.6840/CYCU.2009.00902

摘要

本課題的研究目的在於探討葡萄糖感測電極之選擇性半透膜在人體體溫環境下偵測葡萄糖之特性表現。所使用的半透膜包括硫醇基丙基三甲氧基矽烷(MPTMS)溶膠-凝膠、Nafion及非導電性聚苯胺(PAn)，分別塗附在三支製作方式相同的感測電極上。電極的製作是將導電性聚苯胺(PA)以循環伏安法電聚合的方式聚合於白金(Pt)工作電極表面，再以電吸附法將葡萄糖氧化酵素(GOx)吸入PA之內，最後，再將半透膜滴附或電聚合於電極之上以強化GOx之固定。所製作完成之三種葡萄糖感測電極分別稱之：MPTMS(5%)/GOx-PA/Pt、Nafion(0.15%)/GOx-PA/Pt和PAn(2-cycle)/GOx-PA/Pt。量測葡萄糖是在10 mL之0.1M，pH 7.0，37 oC磷酸鹽緩衝溶液(PBS)中，電位+0.5 V條件下操作。實驗結果顯示MPTMS(5%)/GOx-PA/Pt、Nafion(0.15%)/GOx-PA/Pt和PAn(2-cycle)/GOx-PA/Pt電極的偵測線性範圍都可到達10 mM的葡萄糖濃度，線性相關係數(R值)分別為0.9921、0.9922和0.9897，偵測極限為0.02、0.04和0.04 mM，相對標準偏差RSD則為1.75、2.860和2.72% (n=10)。就電極保存在37 oC的PBS中而言，以MPTMS塗附的電極其半生期10天為最長；Nafion塗附的電極次之，為8天；PAn塗附的電極6天為最短。此外，MPTMS，Nafion和PAn所修飾的電極，其訊號在第2～6天中分別維持在75~80，65~75和50~75%。因此，在體溫環境中，MPTMS比Nafion和PAn修飾電極有較好的感測穩定性。另一方面，從掃描式電子顯微鏡觀察三種半透膜在4、25和37 oC的表面形態，結果顯示，當溫度上升三種半透膜的孔洞都有增大的趨勢，酵素流失的機率因而增大，吾人認為這是溫度上升致使訊號下滑的可能因素之一。根據本研究探討的結果顯示，感測電極在體溫環境的保存下，其功能壽命都大為縮短，因此，如何延長感測電極的功能壽命，仍將是未來持續研究的重要課題。

關鍵字

聚苯胺 ； 氟烯磺酸聚合物 ； 葡萄糖生物感測器 ； 選擇性半透膜 ； 硫醇基丙基三甲氧基矽烷

並列摘要

The purpose of this study is to research the measurement performance assessment of glucose biosensors specifically on perm-selective membranes in the environment of 37 oC for long period of time. Membranes of (3-mercaptopropyl)trimethoxysilane (MPTMS), Nafion and non-conducting poly-aniline (PAn) were coated on three electrodes individually. Each of these electrodes was prepared with the following procedures: electro-polymerization of conducting poly-aniline (PA) on the disc surface of a platinum (Pt) working electrode by cyclic voltammetry method and then electro-chemical absorption of glucose oxidase (GOx) into the PA matrix. The electrodes, GOx-PA/Pt, prepared in this manner were then immobilized by one of the membranes either in dropping or with electro-polymerization technique. Effort was made so that three electrodes were optimized in measuring glucose. These completed electrodes are noted as MPTMS(5%)/GOx-PA/Pt, Nafion(0.15%)/GOx-PA/Pt and PAn(2-cycle)/GOx-PA/Pt. It must be noted that after the completion of the fabrication, these electrodes were stored and operated all time in a 0.1 M, pH 7.0, 37 oC phosphate buffer solution (PBS). When they were used to measure glucose, an operating potential of +0.5 V was applied. The experimental results of measuring glucose by the electrodes of MPTMS(5%)/GOx-PA/Pt, Nafion(0.15%)/GOx-PA/Pt, and PAn(2-cycle)/GOx-PA/Pt show that the linear range was all up to 10 mM; the correlation coefficient (R) was 0.9921, 0.9922 and 0.9897, respectively; the detection limit was 0.02, 0.04 and 0.04 mM, respectively; and the relative standard deviation (RSD) was 1.75, 2.86 and 2.72% (n=10), respectively. According to the results of the electrode functional stability study, the half-life times of the MPTMS-modified, Nafion-modified and PAn-modified were 10, 8 and 6 days, respectively. Importantly, the residual response of the MPTMS-modified electrode steadily maintained at 75~80% during the assessment period between the second and the sixth days. Based on these study performance results, we conclude that the MPTMS-modified electrode is superior to the electrodes of Nafion- and PAn-modified in the temperature environment of 37 oC. In addition, the morphology of the perm-selective membranes stored in PBS temperatures at 4, 25 and 37 oC was examined by scanning electron microscopy (SEM). The results show that the pore sizes of the perm-selective membranes were enlarged when the storage temperature increases. This potentially caused the GOx leakage leading to the decrease of the glucose current responses measured by the electrodes. This finding is important for the development of glucose biosensors using MPTMS, Nafion and none conducting poly-aniline as the perm-selective membrane.

並列關鍵字

Nafion ； Poly-aniline ； Glucose biosensors ； Perm-selective membranes ； (3-mercaptopropyl)trimethoxysilane

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