Direct Electrochemistry And Its Application For Catalysis Reactions Of Chloroperoxidase At GC Modified With SWNTs

The carbon nanotubes (CNTs) have been widely applied in the field of electrochemistry and biosensors in recent years. The direct electrochemistry of various biological enzymes has been observed at electrode modified with CNTs. According to the pretreatment of CNTs mixed with HNO3 and H2SO4, rich-functionalized carbon nanotubes was obtained, which was greater surface area and rich surface functional group. In this study, single wall carbon nanotubes (SWNTs) were chosen to use as the modified materials of electrode.By experiment compared, Nafion was selected as a disperser to disperse carbon nanotubes. The myoglobin (Mb) was immobilized by dropped the mixture of carbon nanotubes dispersed solution and myoglobin solution onto glassy carbon (GC) electrode surface. The study on electrochemical behaviors of Mb-SWNTs-Nafion/GC modified electrode can give us some experience to further study of CPO-SWNTs- Nafion/GC modified electrode. The results showed that Mb can be immobilized onto the surface of GC electrode excellently. A quasi-reversible redox peaks can be observed on the cyclic voltammograms at Mb-SWNTs-Nafion/GC modified electrode. And the results of cyclic voltammetry with different scan rates revealed that the direct electron transfer is a reaction controlled by the surface adsorption process. The results also showed that the immobilized Mb showed effective electrocatalytic activity toward the reduction of O2. The fabrication of the modified electrode is simple and the modified electrode has a good stability.The CPO-SWNTs-Nafion/GC electrode has been fabricated, and the direct electron transfer reaction of CPO can be observed. The results showed that the electron transfer between the immobilized CPO and the GC electrode was a quasi-reversible electrode reaction, which is controlled by the surface adsorption process. The dependence of E0'on solution pH with a slop of - 49.2 mV/pH, indicated that redox of the CPO is a one electron reaction with one protons transfer.In this study, CPO-SWNTs-Nafion/GC electrode have been applied to catalyze the chlorination experiment of Monochlorodimedone (MCD). The results of UV showed that MCD has been catalyzed to dichlorodimedone (DCD) with CPO-SWNTs-Nafion/GC modified electrode and has a good total transformation of the number, which was higher than the others reported in the former literature. However, the problem of enzyme inactivation was still existing, combining with the research of other students in our group and the literature which has been reported, the response was that a higher concentration of H2O2 localized near the electrode surface, which is generated by the electrolysis at constant potential. During the DCD chlorization process, the H2O2 did not participate the reaction or diffuse in time. This is the reason why CPO immobilized on electrode surface lost their activities.