| 摘要: | 本研究以石墨烯(graphene)為基材，利用超臨界二氧化碳(supercritical carbon dioxide, scCO2)合成鈀奈米粒子於其上，製成複合材料。超臨界二氧化碳具良好濕潤性之優點，合成之奈米粒子能均勻分散在石墨烯基材上，大幅地增加反應表面積。研究結果顯示，利用超臨界流體製備之複合材料，應用於非酵素型(non-enzymatic)電化學生化感測，擁有良好的偵測感度。 超臨界流體合成鈀奈米粒子披覆於不同的碳基材上-石墨烯與多壁奈米碳管，分別感測抗壞血酸(ascorbic acid, AA)、多巴胺(dopamine, DA)與尿酸(uric acid, UA)，石墨烯的感測靈敏度略小於多壁奈米碳管；藉由離子液體的輔助，實驗數據顯示，可增強其電子傳遞動能與效率，大幅地改善兩者的電化學訊號，其中利用石墨烯做為載體能獲得比多壁奈米碳管者更佳的感測性能。 超臨界二氧化碳合成之鈀/石墨烯(scCO2 Pd/Graphene)複合材料為感測電極材料，使用五種不同離子液體輔助，分別為1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6)、1-butyl-1-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (BMP-NTf2)、1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA)、1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide (EMI-NTf2)與1-ethyl-3-methylimidazolium dicyanamide (EMI-DCA)，並就離子液體對感測的影響做系統性地探討。透過結合不同離子液體輔助，同時感測接近人體血液濃度之抗壞血酸、多巴胺與尿酸，EMI-DCA與BMP-DCA輔助偵測，可最有效地增加感測電化學訊號。偵測葡萄糖時，則以BMP-NTf2輔助下，具極佳的感測靈敏度。 藉由EMI-DCA 與BMP-NTf2兩種不同性質之離子液體輔助，同時偵測抗壞血酸與葡萄糖，可成功地有效分離兩者的氧化電位及電流，暗示著可針對不同的待測物質，設計合適的離子液體，研究結果指出離子液體將有潛力取代酵素(enzyme)，達到良好靈敏度與選擇性之目的。 In this study, we use graphene as the supporting material. Pd/Graphene nanocomposite is successfully synthesized using a supercritical carbon dioxide (scCO2) deposition technique. Due to good wettability between scCO2 and graphene, the reduced Pd nanparticles are highly dispersed and uniformly loaded on graphene. The scCO2 Pd/Graphene nanocomposite shows a superior sensing performance in non-enzymatic biosensor applications. We have constructed Pd nanoparticles on graphene and multi-walled carbon nanotubes (MWCNTs) substrates with the aid of scCO2. Without incorporating ionic liquid (IL), the electrochemical sensitivity of the Pd/Graphene is less than that of the Pd/MWCNTs. With IL incorporation, the sensing signals of both the composites can be significantly increased. IL plays a role of improving electron transfer kinetics and enhances electrocatalytic activity to ascorbic acid (AA), dopamine (DA), and uric acid (UA) oxidation. The Pd/Graphene/IL shows a higher current response and a wider peak potential separation as compared to those of the Pd/MWCNTs/IL. This result shows that the Pd/Graphene/IL is quite promising for biosensor applications. We have mixed Pd/Graphene with different ILs. Five different ILs are used in this study, including 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6), 1-butyl-1-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (BMP-NTf2), 1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA), 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide (EMI-NTf2), and 1-ethyl-3-methylimidazolium dicyanamide (EMI-DCA). We have systematically evaluated the performance of ILs for optimizing the electrochemical biosensing performances. Among the ILs studied, EMI-DCA can most effectively improve the electrochemical sensitivity of the Pd/Graphene nanocomposite towards AA, DA and UA; while the BMP-NTf2 is more suitable for glucose detection. For simultaneous detection of AA and glucose, satisfactory selectivity of the composite electrode can be achieved by incorporating appropriate ILs. The research findings show that ILs could be potential substitutes for enzymes in electrochemical biosensor applications. |
