Electron transfer reactions of glucose oxidase at Au111 electrodes modified with phenothiazine derivatives.
Electron transfer reactions of glucose oxidase at Au111 electrodes modified with phenothiazine derivatives.
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DOI：
10.1021/ac0502504
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发表时间：
2005-07
影响因子：
7.4
通讯作者：
S. Nanjo;K. Ishii;T. Ueki;S. Imabayashi;M. Watanabe;K. Kano
中科院分区：
文献类型：
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作者：
S. Nanjo;K. Ishii;T. Ueki;S. Imabayashi;M. Watanabe;K. Kano
研究了共价键合到 Au(111) 电极上的 3-(10-吩噻嗪基)丙酸 (PT-PA) 和吩噻嗪标记的聚环氧乙烷 (PT-PEO1000) 介导的葡萄糖氧化酶 (GOx) 的催化反应。 PT-PA 和 PT-PEO1000 与 2-氨基乙硫醇 (AET) 反应，然后在金表面形成自组装单层 (SAM)。固定在 AET 的 SAM 上的 PT 基团充当电极和溶液中自由扩散的 GOx 的 FAD 中心之间电子转移 (ET) 的有效介体。使用新导出的方程根据催化电流估算的 ET 速率常数，PT-PA 改性系统 (1.1 x 10(5) dm(3) mol(-1) s(-1)) 比 PT-PEO1000 系统 (1.4 x 10(4) dm(3) mol(-1) s(-1)) 大 1 个数量级。 ET 速率常数的数量级与我们之前研究的 GOx 混合系统 (Anal. Chem. 2003, 75, 910-917) 形成鲜明对比，其中 PEO 间隔基的存在提高了 ET 反应速率。由于PEO链的高迁移率导致电极界面处的表观PT浓度降低，导致酶-介体复合物的形成效率低，这可能是PT-PEO1000对于FAD基团和固定在电极上的PT(+)之间的ET的介导能力低于PT-PA的可能原因。 GOx分子渗透到单层中以及部分PT基团与GOx分子的可及性受到抑制也可能是电极上厚修饰的PT-PEO1000介导能力较低的原因。
The catalytic reaction of glucose oxidase (GOx) mediated by 3-(10-phenothiazyl)propionic acid (PT-PA) and phenothiazine-labeled poly(ethylene oxide) (PT-PEO1000) that are covalently bonded to Au(111) electrodes has been investigated. The PT-PA and PT-PEO1000 are reacted with 2-aminoethanethiol (AET), followed by the formation of a self-assembled monolayer (SAM) onto the Au surface. The PT group immobilized on the SAM of AET acts as an effective mediator for the electron transfer (ET) between the electrode and the FAD center of freely diffusing GOx in solution. The ET rate constant estimated from the catalytic current using a newly derived equation is larger by 1 order of magnitude for the PT-PA-modified system (1.1 x 10(5) dm(3) mol(-1) s(-1)) than for the PT-PEO1000 system (1.4 x 10(4) dm(3) mol(-1) s(-1)). The order of the magnitude of the ET rate constant clearly contrasts with the GOx hybrid systems that we previously investigated (Anal. Chem. 2003, 75, 910-917), in which the presence of the PEO spacer enhances the ET reaction rate. The reduction in the apparent PT concentration at the electrode interface due to the high mobility of the PEO chain, leading to low efficiency in the formation of an enzyme-mediator complex, is a possible reason for the lower mediation ability of PT-PEO1000 than that of PT-PA for the ET between the FAD group and PT(+) immobilized on the electrode. Inhibition of the penetration of GOx molecules into the monolayer and of the accessibility of some part of PT groups to GOx molecules could also be reasons for the lower mediation ability of PT-PEO1000 thickly modified on the electrode.