维生素B_(12)在碳纳米管修饰玻碳电极上的电化学行为

The Electrochemical Behavior of Vitamin B_(12) at a Glassy Carbon Electrode Modified with Carbon Nanotubes

固载于碳纳米管上的维生素B12(VB12)能保持良好的生物活性,在碳纳米管修饰玻碳电极(CNT/GC)表面能进行有效的、稳定的直接电子转移,其循环伏安曲线表现出两对氧化还原峰,式量电位EO'几乎不随扫速(至少在10～100 mV/s的扫速范围内)而变化,其平均值分别为(0.173±0.004)V和(-0.773±0.004)V(vs.SCE,pH 7.0);式量电位与溶液pH的关系表明VB12的直接电化学是无质子参与的电极过程。进一步实验结果表明固定在CNT/GC电极上的VB12能保持其对H2O2的生物电催化活性,可用于H2O2的高灵敏度检测;H2O2浓度在4×10-5mol/L～4.5×10-2mol/L范围内时,VB12催化还原电流与H2O2浓度有良好的线性关系。

Vitamin B12 was immobilized on a CNT/GC electrode. The experimental results showed that CNTs could have promotion effect on the direct electron transfer of Vitamin B12. Cyclic vohammetrie results showed two pairs of redox peaks, which corresponded to the direct electron transfer of Vitamin B12, the average values of E0 are （0. 173 ±0.004 ） V and （ -0. 773 ±0.004） V （ vs. SCE,pH 7.0） in the phosphate buffer solution in the scan rate range of 10 ～ 100 mV/s. The dependence of E0 on pH indicated that the direct electron transfer reaction of Vitamin B12 was a one - electron transfer without proton transfer reaction process. The exper- imental results also demonstrated that the immobilized Vitamin Bl2 retained their bioelectroeatalytic aetivity to the reduction of H202 ; the linearity of calibration was between 4× 10 -5 and 4.5 ×10 -2 mol/L.