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  • 學位論文

透過調控聚苯胺傳導層之疏水性提升固態離子選擇電極感測性能

Tuning the Hydrophobicity of Polyaniline Solid Contact for Enhancing the Performance of a Solid-State Ion-Selective electrode

指導教授 : 陳林祈
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摘要


開發固態式離子選擇電極時會面臨離子電子轉移障礙與水層效應(water layer effect)等問題,這些現象使得電極在感測離子時電位訊號不穩定。為改善此一現象,介於選擇薄膜與電極之間的離子電子傳導層因應而生。本研究以導電高分子聚苯胺作為本次研究離子選擇電極之離子電子傳導層,期待聚苯胺之高電導性以及高離子電子移動率對電極之感測性能有增益效果。本研究第一部分為聚苯胺離子電子傳導層之表面結構分析。實驗結果顯示不同電鍍掃描速率:10,20,50,100 mV/s (於本研究中以PANI10,PANI20,PANI50,PANI100代稱)會造成離子選擇電極之親疏水性不同。其中電鍍時間較長之聚苯胺(PANI10)結構緻密並有許多微環摻雜其中,接觸角量測結果達到138度。相比於電鍍時間較短之聚苯胺材料(PANI100)接觸角提高了1.84倍,可見摻雜微環的緻密結構可使聚苯胺疏水性提高以減少水層的滲入,如此則能提高電極在感測時之穩定性。本研究第二部分為聚苯胺傳導層材料之性能探討,在進行二階段的計時電位法量測中,PANI10比起PANI100減少了96%的電位飄移,可見電鍍時間較長之PANI10具有較高的電位穩定性以及電容值。本研究的第三部分為電極感測性能部分,PANI10-鉀離子選擇電極所呈現之鉀離子靈敏度為51.4 mV/decade,偵測極限達10-5M。相較於PANI100-鉀離子選擇電極(靈敏度44.6 mV/decade,偵測極限10-5M) 表現還更好,推論聚苯胺傳導層會隨著其電鍍時間的不同而影響電極之電導性及靈敏度表現。最後,將鈉、鉀、氯、鈣等四個離子與參考電極整合在微型試片上共同感測,實驗結果顯示:PANI10-鈉離子選擇電極於標準液內量測之偵測極限可達到10-6M,相較於PANI100-鈉離子選擇電極的10-5M表現還更好。而鉀、氯、鈣離子選擇電極也呈現同樣的趨勢,故可推測電鍍時間較長之聚苯胺由於其表面較疏水且電容值較高,導致其選擇電極具有較高的靈敏度以及較低的偵測極限。本研究第四部分為離子選擇電極陣列置入牛血清白蛋白中實測。由於感測器長時間與血液接觸其蛋白質會吸附於電極表面,此些吸附過程會大大影響量測時之穩定度。本研究利用修飾添加物之方法探討離子選擇電極陣列在修飾前後之電位飄移程度,實驗結果發現鉀離子選擇電極較不被蛋白質吸附影響其感測效果,氯離子選擇電極則因為蛋白質吸附影響其在BSA當中的感測效果,故本論文探討三種修飾添加物之方式:只修飾F127在參考電極表面、只修飾F127在工作電極表面、參考電極與工作電極表面上皆修飾上F127。由實驗結果得知在參考電極表面上修飾F127可增加實驗之重複性、減少實驗誤差,但對受蛋白質吸附而影響感測效果之電極沒有增益效果。而單在工作電極修飾上F127可以提升電極抗蛋白質吸附能力,只是三重複之實驗誤差卻相當的大。最後,由於近年來人體機能之相關議題隨著科技發展而逐漸被重視,其應用在臨床醫學上日益重要。本研究以可線上監控之微型離子選擇試片為開發目標,將四種離子工作電極(鈉、鉀、氯、鈣)與參考電極整合在同一試片上以達到電極之微型化。

並列摘要


A solid-contact ion-selective electrode (SC-ISE) is a miniature, planar electrochemical ion sensing device and features a laminated structure of ion-selective electrode. The sensitivity and detection limit of an SC-ISE are considerably influenced by its solid contact layer, which should have sufficient high hydrophobicity to prevent a water-layer effect. However, study related to tuning the hydrophobicity of a solid contact layer for improving ISE performance has not been reported. In this study, we choose a polyaniline (PANI)-based solid-contact K+ ISE as a model system, and we assume that the structure of PANI can be controlled by its electrodeposition rate. Furthermore, the difference in structure of PANI can result in different hydrophobicity and thus lead to different ion-sensing performance. PANI was electrodeposited onto a screen-printed carbon electrode (SPCE) with different CV scanning rates (10, 20, 50, and 100 mV/s) between -0.1 V and + 0.9V for 5 cycles. Afterward, a K+ PVC ISM was dropped coated on the PANI/SPCE to result in a K+ SC-ISE. SEM pictures confirm that different CV deposition rates give different surface structures for PANI, which then causes the difference in surface hydrophobicity of PANI, as evident with contact angle. It is found that the smaller CV deposition rate is, the larger the contact angle is obtained. Accordingly, a PANI solid contact prepared with a smaller deposition rate results in better ion-sensing performance. Advanced study indicates that a smaller CV deposition rate shows higher electrochemical capacitance, lower charge-transfer resistance of PANI, too. In conclusion, the PANI solid contact layer’s hydrophobicity can be enhanced by decreasing the CV deposition rate, which can improve ion-sensing sensitivity and detection limit accordingly. Finally, the ion-selective electrode array was placed in the bovine serum albumin (BSA) simulated from human serum concentration. As the sensor bathed in the BSA for a long time and its protein will be adsorbed on the electrode surface. The adsorption process will greatly affect the stability of the measurement. In this study, the effect of modified additive on the potential drift of the ion selective electrode array was studied. The results showed that the potassium ion selective electrode was not affected by protein adsorption. The chloride ion selective electrode was influenced by protein adsorption. In this part, we explore three modifications of the additive: F127 is modified on the surface of the reference electrode only, F127 is modified on the surface of the working electrode only, and F127 is modified on the surface of the reference electrode and the working electrode. It is found that the modification of F127 on the surface of the reference electrode can increase the reproducibility of the experiment and reduce the experimental error. However, modification of F127 on the surface of the reference electrode does not help with anti-protein adsorption. In recent years, the related issues of human care have been paid more attention with the development of science and technology. Its application is becoming more and more important in clinical medicine. In order to avoid the high frequency of blood testing and the electrode production cost, the multiple ion selective electrode array (sodium, potassium, chlorine and calcium) is integrated with the reference electrode in the same piece.

參考文獻


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