Automatic electrochemical micro-pH-stat for biomicrosystems.
Automatic electrochemical micro-pH-stat for biomicrosystems.
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DOI：
10.1021/ac071286u
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发表时间：
2008-01
影响因子：
7.4
通讯作者：
K. Morimoto;M. Toya;J. Fukuda;H. Suzuki
中科院分区：
文献类型：
--
作者：
K. Morimoto;M. Toya;J. Fukuda;H. Suzuki
研制了一种具有自动反馈功能的微电化学pH稳定器。该设备的操作是基于非标准使用的电化学三电极系统与pH敏感的参考电极，Ag/AgCl工作电极，和铱辅助电极，其功能作为致动器，以调整溶液的pH值。电极的组合引起响应于pH值变化的负反馈。pH敏感参比电极电位的漂移导致Ag/AgCl工作电极上的过电位，然后导致电流显著增加。这导致了辅助电极上的水的电解和pH值的快速恢复。可以确认的负反馈功能，以稳定初始状态的变化，以酸性和碱性方向。在乙酸或氨的滴定中表征了pH恒定器的性能。在反馈过程中产生的电荷相对于浓度线性变化。该pH稳定器还可用于尿素酶测定尿素、胰蛋白酶和胃蛋白酶活性的测定，同时保持酶的最适pH。可以通过改变工作电极电位来改变待固定的pH。此外，这两个pH调节器可用于通过将pH值固定在两个位置来在微流通道中形成pH梯度。
A microelectrochemical pH-stat with an automatic feedback function was fabricated. The operation of the device is based on the nonstandard use of an electrochemical three-electrode system with a pH-sensitive reference electrode, a Ag/AgCl working electrode, and an iridium auxiliary electrode that functions as an actuator to adjust the solution pH. The combination of the electrodes caused a negative feedback in response to a pH change. The shift of the potential of the pH-sensitive reference electrode caused an overpotential on the Ag/AgCl working electrode, which then caused a significant current increase. This led to the electrolysis of water on the auxiliary electrode and the rapid recovery of the pH. The negative feedback function to stabilize the initial state could be confirmed for changes to both the acidic and basic directions. The performance of the pH-stat was characterized in the titration of acetic acid or ammonia. The charge generated in the feedback process changed linearly with respect to the concentration. The pH-stat was also used in the determination of urea by urease and that of the activities of trypsin and pepsin while maintaining the optimum pH for the enzymes. The pH to be fixed could be changed by changing the working electrode potential. Moreover, the two pH-stats could be used to form a pH gradient in a microflow channel by fixing the pH values at two positions.