普魯士藍-金奈米粒子複合材料及銅赤血鹽錯合物修飾於氧化銦錫電極之電化學分析應用

Abstract

含有過渡金屬原子的無機化合物藉由自身氧化還原，加速分析物進行氧化還原反應，擁有相當優異的電化學催化能力。本實驗以普魯士藍 (Prussian blue，PB) 結合奈米金粒子 (gold- Prussian blue nanocomposites， (Au-PB)nano ) 之奈米複合材料以及銅赤血鹽 (copper hexacyanoferrate，CuHCF) 錯合物，分別製作奈米複合材料修飾之感測電極，以提升偵測靈敏度並改善電極之電化學穩定性，並成功應用於不同真實樣品之檢測。 本實驗所使用之電極為氧化銦錫 (indium-tin oxide，ITO) 電極，利用微影製程與蝕刻方法，固定其在玻璃基材上的感測面積，可以簡單生產出具備高再現性的ITO電極感測器。之後結合單步驟的電沈積方法，將普魯士藍系列錯合物修飾在ITO電極表面上，製作出可拋棄式的感測電極。修飾方法為將ITO電極置於最佳化混合電鍍液中，以循環伏安法在固定電位區間將ITO電極表面修飾上對分析物具有催化特性之薄膜。本研究第一部分實驗中利用金奈米粒子輔助普魯士藍修飾ITO電極表面，有效提升分析物半胱胺酸 (cysteine，Cys) 之偵測靈敏度，並改善傳統普魯士藍薄膜在電化學上的不穩定性。於最佳化條件下修飾之電極，針對分析物半胱胺酸的安培法偵測極限為 0.03 μΜ (S/N = 3)，線性範圍則在 0.20 μM 到 80.10 μM 之間 (R2 = 0.997)。在尿液樣品中其回收率均高於94.5% (RSD 1.78%) 且不受尿素、尿酸、維生素C與葡萄糖等干擾物之干擾。本研究之第二部分實驗則利用相同修飾方法，於ITO電極表面修飾材料中，利用銅離子部份取代六氰化亞鐵錯合物中心之亞鐵離子，使其產生類似普魯士藍錯合物之結構並令其對聯胺 (hydrazine) 有催化能力。最佳化條件下修飾之電極在聯胺之定量分析中，線性範圍為 5.00 μΜ 到 1133.20 μM 之間 (R2 = 0.998)，偵測極限可達1.04 μΜ (S/N=3)。於不同來源之水樣品中，其回收率達97.5% 以上 (RSD 4.36%) 且成功排除多種水樣品中常見陽離子與陰離子產生之干擾。 本研究的結果相較於以往的文獻，僅需要以簡單之單步驟電沉積修飾，即可製造出具高靈敏度、高精確度、高穩定性與可拋棄性之奈米複合材料修飾電極，且可分別應用於不同真實樣品之檢測。

Metal hexacyanoferrates (MHCF), including ferric hexacyanoferrate (also called Prussian blue, PB) and copper hexacyanoferrate (CuHCF) , were widely used as electrontransfer mediator in electrochemical biosensors. Various methods were used in preparing MHCF modified electrodes such as electrodeposition and self-assembled monolayer and applicated in different fields.

In the first part of this study, a gold-Prussian blue nanocomposite (Au-PB)nano) film modified indium tin oxide (ITO) electrode was fabricated in order to detect L-cysteine (Cys) that takes place in physiology and causing serious problem in health. The gold-PB nanocomposite film was simply electrodeposited by one step cyclic voltammetry (CV) from 0.0 V to 1.0 V for 40 cycles in the mixture of 2 mM HAuCl4 and ferric cyanide. The fabricated electrode was characterized by voltammetry and scanning electron microscopy (SEM) for its electrochemical performance and surface morphology. The oxidation potential of Cys at the operation potential that fixed at 1.2 V (vs. Ag/AgCl) in pH 2.4 phosphate buffer solution (PBS) was measured by amperometric sensing. The linear range of Cys sensing by using electrodes that fabricated in optimized conditions was from 0.20 μM to 80.10 μM (R2 = 0.997 ) with low detection limit of 0.03 μΜ (S/N=3). The detection sensitivity for Cys is 2.634 AM-1cm-2. The recoveries of spiked Cys in human urine samples were higher than 94.8% with RSD 1.78% showed that the (Au-PB)nano modified ITO electrode was suitable for detecting cysteine in real sample with good performance.

Hydrazines, recognized as carcinogenic and hepatotoxic substances were interested in both the chemical and pharmaceutical industry. In the second experiment, copper hexacyanoferrate (CuHCF) modified ITO electrode by single step electrodeposition was fabricated. The CuHCF film on the electrode was formed by dipping the ITO electrode in the mixed solution containing both 1 mM CuSO4 and ferric cyanide by cyclic voltammetry (CV) from 0.0 V to 1.0 V for 40 cycles. The CuHCF film on the surface of modified electrode was also characterized by SEM. The electrocatalytic oxidation of hydrazine at the operation potential of 0.65 V (vs. Ag/AgCl) in 0.1 M NaNO3 was measured by amperometric sensing. The sensitivity and the detection limit of the electrode were 61.631 μAmM-1cm-2 and 1.04 μΜ (S/N=3), separately. The linear range of calibration curve was from 5.00 μM to 1133.20 μM (R2 = 0.998). The recoveries and RSDs of three different water samples that spiked 8 μM of hydrazine were better than 97.5 and 4.36%, separately.

The performance of above mentioned that PB combined gold nanoparticles and its analogue, CuHCF, modified electrodes showed easy fabrication, rapid response, high sensitivity, freedom of interferences and low cost (disposable) in analytical applications.