基于明胶-碳纳米管的辣根过氧化物酶修饰电极在离子液体中的直接电化学

Direct Electrochemistry of a GCE Modified with HRP/Gel-MWCNTs in Ionic Liquid [BMIM]BF_4

制备了明胶(Gel)-多壁碳纳米管(MWCNTs)纳米复合物,将其修饰在玻碳电极表面,再吸附辣根过氧化物酶(HRP),制得明胶-多壁碳纳米管-辣根过氧化物酶修饰电极(Gel-MWCNTs-HRP/GCE)。该修饰电极在PBS中的循环伏安图上出现了一对峰形良好、几乎对称的氧化还原峰,式量电位为-0.356 V(vs.SCE),表明包埋在Gel-MWCNTs中的HRP与电极之间发生了直接电子传递。当扫速在20～180 mV/s时,氧化峰电流(Ipa)与还原峰电流(Ipc)均与扫速成正比,表明电极过程是受电子传递速率控制的表面传质过程。运用循环伏安法研究了修饰电极的电化学特性,探讨了工作电位、pH值、干扰物质等对修饰电极的影响。实验结果表明,HRP在修饰电极表面能有效和稳定地进行直接电子转移,并保持了其对过氧化氢(H2O2)的生物催化活性。进一步研究发现,在含有亲水性离子液体1-丁基-3-甲基咪唑四氟硼酸([BMIM]BF4)的溶液中,修饰电极对H2O2显示出更灵敏的催化活性,其线性范围为2.0×10-7～0.13 mol/L,检出限(S/N=3)为2.3×10-8mol/L。该电极具有灵敏度高、重现性及稳定性好、使用寿命较长等优点,同时还显示了较好的抗干扰能力。

A novel hydrogen peroxide biosensor was constructed based on horseradish peroxidase （HRP） immobilized onto glass carbon electrode （GCE）, which was modified with the nanocomposite of gelatin and multi-walled carbon nanotubes （MWCNTs）. The electrochemistry and electrocatalysis of the modified biosensor were investigated. A pair of well-defined and nearly symmetrical redox peaks with a formal potential of -0. 356 V （vs. SCE） in PBS were observed, which attribute to the direct electron transfer between the entrapped HRP and the electrode. The redox peak current was proportional to scan rate in the range of 20 - 180 mV/s, indicating that the process was affected by electronic transfer electrode rate control surface of mass transfer process. The electrochemical characteristics of the modified electrode were investigated by cyclic vohammetry. The effects of applied potential, solution pH and interferences on the biosensor were discussed. The results demonstrated that HRP could display an excellent electrocatalytic response to the reduction of hydrogen peroxide. Fur thermore, the biosensor exhibited a more sensitive catalytic activity on H202 in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate （[ BMIM ] BF4 ）, than that in PBS buffer. A wide linear response to H202 in the range of 2. 0 x 10^-7 -0. 13 mol/L was obtained with a detection limit（ SIN = 3 ） of 2. 3 x 10-s mol/L. The modified electrode exhibited the advantages of good stability, wide linear range and lower detection limit as well as a certain anti-interference ability.