"以聚(3,4-乙烯二氧噻吩)修飾黃金電極製備固態pH與碳酸根離子感測試片之研究"

Abstract

器官晶片作為取代動物實驗的前瞻技術而備受矚目。為了有效追蹤細胞代謝所造成的環境變化，感測器勢必須微型化。固態式離子選擇電極提供了一監測pH值及二氧化碳濃度的方式，然其仍受限於電位不穩定及記憶效應。是故，本研究旨在開發平面固態式的氫離子及碳酸根離子選擇電極，並藉由調控聚(3,4-乙烯二氧噻吩) (poly(3,4-ethylenedioxythylphene, PEDOT))離子電子傳導層的相對離子種類及離子選擇薄膜的製程參數，改善離子選擇電極的靈敏度、電位穩定性及重複性。離子電子訊號轉換效率取決於PEDOT的氧化還原反應，因此PEDOT需具備高化學穩定性及贗電容值。定電位電鍍的條件下，以BF4-作為相對離子的PEDOT滿足此條件。以其製備的氫離子選擇電極與碳酸根離子選擇電極的性能表現為最佳，其靈敏度分別為59.16 mV/pH、24.37 mV/decade，以及電位穩定性分別為7.12 μV/s、14.08 μV/s。氫離子選擇電極的離子選擇薄膜厚度增加可舒緩離子流效應並降低記憶效應影響，因此離子選擇薄膜以10μL的量滴覆三次的組別電位重複性為最佳。而碳酸根離子選擇電極的離子選擇薄膜厚度不影響電位重複性，並考量靈敏度與電位穩定性，其以10μL的量單次滴覆的組別表現最佳。改良製程參數後的氫離子與碳酸根離子選擇電極置於1x PBS溶液下進行重複量測 (n = 5)的量測電位標準差分別為1.06 mV及1.33 mV。最後，將氫離子與碳酸根離子選擇電極於細胞培養基感測的結果顯示，兩電極於含有血清的溶液中也可維持高度的電位穩定性並且能量測到一週的細胞培養基離子濃度變化。

Organs-on-a-chip is attracting for the advanced technology as an alternative to the animal models. To monitoring the environmental changes caused by cellular metabolism effectively, the sensor must be miniaturized. Solid-state ion-selective electrodes (SS-ISEs) provide a way to measure pH and dissolved carbon dioxide system, but are still limited by the potential instability and the memory effect. In this study, we used poly(3,4-ethylenedioxythiophene) (PEDOT) as ion-to-electron transducer (IET) to construct the solid-state pH electrode and solid-state carbonate-selective electrode. We aimed to improve the potential stability and potential repeatability of SS-ISEs by tuning the counter ion of IET and the casting method of ion-selective membrane (ISM). Firstly, the efficiency of signal transfer between ion and electron is related to the redox reaction of PEDOT. For this purpose, high electrochemical stability and high pseudocapacitance of PEDOT is needed. Under the constant potential electrodeposition method, PEDOT with BF4- ion met the requirement. The sensitivity and potential stability of hydrogen-ISE and the carbonate-ISE were 59.16 mV/pH, 7.12 μV/s and 24.37 mV/decade, 14.08 μV/s, respectively. Secondly, increasing in the thickness of ISM of hydrogen ISE could reduce ionic flux and the memory effect, so multiple times drop coating of ISM was optimal. But the carbonate-ISE was opposite, ISE with single drop of ISM could have best sensitivity, potential stability and the potential repeatability, so single time drop coating of ISM was optimal. After tuning the parameters of the manufacturing process, the hydrogen-ISE and carbonate-ISE were placed in a multi-ion solution for repeated measurement (n = 5) with excellent potential repeatability, and the values were 1.06 mV and 1.33 mV, respectively. Finally, the performance of the hydrogen-ISE and carbonate-ISE in the cell culture medium showed that the two electrodes could maintain a high potential stability in the serum-containing solution and could measure the difference in concentration of the cell culture medium for different days.