血红蛋白在壳聚糖修饰碳纳米管上的电化学特性及对过氧化氢的电催化分析

Electrochemical Characteristics of Hemoglobin on Multi-walled Carbon Nanotubes Modified with Chitosan and Catalytic Assay for Hydrogen Peroxide

用壳聚糖对多壁碳纳米管进行修饰，构建了一种用于固定血红蛋白的新型复合材料，并研究了血红蛋白在该碳纳米管上的电化学性质及其对过氧化氢的电催化活性。扫描电镜结果表明，壳聚糖修饰的多壁碳纳米管呈单一的纳米管状，并能均匀分散在玻碳电极表面。紫外光谱分析表明血红蛋白在该复合膜内能很好地保持其原有的二级结构。将该材料固定在玻碳电极上后，血红蛋白能成功地实现其直接电化学。根据峰电位差随着扫描的变化，计算得到血红蛋白在壳聚糖修饰的碳纳米管膜上的电荷转移系数为0．57，表观电子转移速率常数为7．02s^-1。同时，该电极对过氧化氢显示出良好的催化性能，电流响应信号与H2O2浓度在1．0×10^-6-1．5×10^-3mol／L间呈线性关系，检出限为5．0×10^-7mol／L。修饰电极显示了良好的稳定性。

A novel composite material of multi-walled carbon nanotubes （MWCNTs） modified with ehitosan was prepared to immobilize redox protein hemoglobin（Hb）. The electrochemical characteristics of Hb immobilized on the modified MWCNTs and its electrocatalytic activity toward H2O2 were also studied. Scanning electron microscopy images showed that the modified MWCNTs exhibited a single nano tubiform and could well dispersed on the glassy carbon electrode. UV - Vis spectra indicated that Hb could keep its original secondary structure well in the composite film. Cyclic voltammogram of Hb - chitosan-MWCNTs film modified glassy carbon electrode showed a pair of well-defined and quasi-reversible redox peaks for Hb Fe （ Ⅲ ）/Fe （ Ⅱ ）, indicating that a direct electron transfer between Hb and GC electrode occurred. The charge-transfer coefficient and the apparent electron-transfer rate constant for Hb on chitosan modified MWCNTs were calculated to be 0. 57 and 7.02 s^-1 respectively. The formal potential （ V^0＇） of-0. 324 V（vs SCE） was observed, which was a characteristic potential of Hb heine Fe（ Ⅲ ）/Fe（ Ⅱ ） redox couple. The dependence of formal potential （V^0＇） on solution pH indicated that one-proton transfer was coupled to each electron transfer in the direct electron-transfer reaction. Furthermore, the modified electrode showed excellent electrocatalytic activity toward H2O2. The electrocatalytic current signals were linear with the concentration of H2O2 in a wide range of 1.0 × 10^-6 _ 1.5 × 10^-3 mol/L with a detection limit of 5.0× 10^-7 mol/L. The modifled electrode also exhibited good stability in one week.