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.

Graphical abstract One dimensional Au nanoparticles-functionalized magnetic N-doped carbon nanotubes have been fabricated, which was employed as a novel matrix for enzyme immobilization to develop highly sensitive biosensors. Highlights • A convenient and efficient method was developed to prepare magnetic NCNTs@Fe 3 O 4 supported Au NPs. • One-dimensional NCNTs@Fe 3 O 4 @Au composite was exploited as a biosensing scaffold to entrap cyt c. • The magnetic NCNTs@Fe 3 O 4 @Au based sensor could avoid the modification on the electrode and realize the direct detection in the solution. • The resultant biosensors displayed good performance for the detection of H 2 O 2 with a low detection limit of 0.3 μM. 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 Fe 3 O 4 and Cu nanoparticles (NPs) were integrated into the NCNTs to obtain N-doped carbon@Fe 3 O 4 -Cu nanotubes (NCNTs@Fe 3 O 4 @Cu) through a one-pot high temperature decomposition procedure. Then, Au NPs were assembled on the magnetic NCNTs to obtain NCNTs@Fe 3 O 4 @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@Fe 3 O 4 @Au composite, the cyt c/NCNTs@Fe 3 O 4 @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 H 2 O 2 with an extraordinary low detection limit of 0.3 μM, which revealed potential application for fabricating novel electrochemical biosensors. [ABSTRACT FROM AUTHOR]