碳纳米管电极上辣根过氧化物酶的直接电化学

Direct Electrochemistry of Horseradish Peroxidase at a Carbon Nanotube Electrode

制备了碳纳米管修饰玻碳电极 (CNT/GC) .将辣根过氧化物酶 (HRP)固定在CNT/GC电极表面 ,形成HRP CNT/GC电极 .研究了HRP的直接电子转移 .实验结果表明 ,HRP在CNT/GC电极表面能进行有效和稳定的直接电子转移反应 ,其循环伏安曲线上表现出一对良好的、几乎对称的氧化还原峰 ;式量电位E0 ′几乎不随扫速 (至少在 2 0～ 10 0mV/s的扫速范围内 )而变化 ,其平均值为 (-0 3 19± 0 0 0 2 )V (vs .SCE ,pH 6 9) ;HRP在CNT/GC电极表面直接电子转移的速率常数为(2 0 7± 0 5 6)s-1;式量电位E0 ′与溶液pH的关系表明HRP的直接电化学是 (1e + 1H+ )的电极过程 .进一步的实验结果显示 ,固定在CNT/GC电极表面的HRP能保持其对H2 O2 还原的生物电催化活性 ,而且能快速地响应H2 O2 浓度的变化 .本文制备碳纳米管修饰电极和固定酶的方法具有简单和易于操作等优点 。

Horseradish peroxidase (HRP) immobilized on the surface of the carbon nanotube modified glassy carbon electrode (HRP-CNT/GC) can undergo effective and stable direct electron transfer reaction. The cyclic voltammetric results indicate that the HRP-CNT/GC electrode exhibits a pair of well-defined and nearly symmetrical redox peaks in 0.1 mol/L phosphate buffer solution. Its formal redox potential, E 0′, is almost independent on the scan rates, the average value of E 0′ is (-0.319±0.002) V (vs. SCE, pH 6.9) in the phosphate buffer solution (pH 6.9) in the scan rate range of 20～100 mV/s. The dependence of E 0′ on the pH of the buffer solution indicates that the direct electron transfer of HRP is a one-electron-transfer reaction process coupled with one-proton-transfer. The experimental results also demonstrated that the immobilized HRP retained its bioelectrocatalytic activity for the reduction of H 2O 2 and the HRP-CNT/GC electrode can rapidly respond to the change of the concentration of H 2O 2. The method presented here can be easily extended to obtain the direct electrochemistry of other redox enzymes or proteins.