Department of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China.
J Phys Chem B. 2010 Mar 11;114(9):3380-6. doi: 10.1021/jp912203d.
The lectin protein concanavalin A (Con A) and the glycoenzyme horseradish peroxidase (HRP) were assembled into {Con A/HRP}(n) layer-by-layer films on electrodes mainly by biospecific affinity between them. The cyclic voltammetric (CV) response of ferricyanide (Fe(CN)(6)(3-)) at {Con A/HRP}(n) film electrodes was very sensitive to the environmental pH. The peak currents of Fe(CN)(6)(3-) were quite large at pH 4.0 but greatly suppressed at pH 9.0, demonstrating reversible pH-sensitive "on-off" behavior. This property could be used to realize pH-controlled electrochemical reduction of H(2)O(2) catalyzed by HRP immobilized in {Con A/HRP}(n) films and mediated by Fe(CN)(6)(3-) in solution. The modulation of the solution pH was also realized by in situ biochemical reactions with various enzymes in solution and was used to tune the pH-switchable bioelectrocatalysis. The possible mechanism of the pH-responsive on-off behavior of the films toward the probe was explored, and the electrostatic interaction between the films and the probe is believed to play a key role in deciding the pH-sensitive behavior of the films. This "smart" interface may be used to establish a foundation for fabricating novel pH-controllable electrochemical biosensors based on bioelectrocatalysis with immobilized enzymes.
凝集素蛋白伴刀豆球蛋白 A（Con A）和糖基酶辣根过氧化物酶（HRP）通过它们之间的生物特异性亲和力被组装到电极上的 {Con A/HRP}(n) 层层薄膜中。{Con A/HRP}(n) 薄膜电极上铁氰化物（Fe(CN)(6)(3-))的循环伏安（CV）响应对环境 pH 非常敏感。在 pH 4.0 时，Fe(CN)(6)(3-)的峰电流非常大，但在 pH 9.0 时大大抑制，表现出可逆的 pH 敏感“开-关”行为。这种性质可用于实现 HRP 固定在 {Con A/HRP}(n) 薄膜中并通过溶液中的 Fe(CN)(6)(3-)介导的 H(2)O(2)的电化学还原的 pH 控制。溶液中各种酶的原位生化反应也实现了溶液 pH 的调制，并用于调节 pH 开关型生物电化学催化。对薄膜对探针的 pH 响应开-关行为的可能机制进行了探讨，并且认为薄膜和探针之间的静电相互作用在决定薄膜的 pH 敏感性行为方面起着关键作用。这种“智能”界面可用于为基于固定化酶的生物电化学催化构建新型 pH 可控电化学生物传感器奠定基础。
