Direct electrochemistry of cytochrome c immobilized on one dimensional Au nanoparticles functionalized magnetic N-doped carbon nanotubes and its application for the detection of H2O2

Abstract In recent years, the fabrication of noble metal functionalized magnetic carbon nanotubes for a variety of novel biosensors has aroused considerable interest owing to their synergistic improved sensitivity. In the paper, the Fe3O4 and Cu nanoparticles (NPs) were integrated into the NCNTs to obtain N-doped carbon@Fe3O4-Cu nanotubes (NCNTs@Fe3O4@Cu) through a one-pot high temperature decomposition procedure. Then, Au NPs were assembled on the magnetic NCNTs to obtain NCNTs@Fe3O4@Au composite by galvanic replacement with Cu NPs. The resultant composite had provided a friendly platform for enzyme immobilization to develop highly sensitive biosensors. After the cytochrome c(cyt c) was accumulated by NCNTs@Fe3O4@Au composite, the cyt c/NCNTs@Fe3O4@Au gathered to the surface of electrode with an external magnet. Thus, the sensitivity of designed biosensor could be further improved, and most of electrochemical interferences could be excluded. Benefiting from the unique hybrid structure of the composite, the direct electron transfer of cyt c was highly facilitated and the constructed biosensors exhibited good performance for the detection of H2O2 with an extraordinary low detection limit of 0.3 μM, which revealed potential application for fabricating novel electrochemical biosensors.