Bamboo-like CNx nanotubes for the immobilization of hemoglobin and its bioelectrochemistry

The novel bamboo-like nitrogen-doping CNx nanotubes were firstly used for the immobilization of hemoglobin (Hb) and their bioelectrochemical behaviors were studied. It was clearly observed by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) that Hb could be strongly adsorbed on the surface of CNx nanotubes. The CV results of Hb/CNx nanotubes modified electrode showed a pair of well-defined, quasi reversible redox peaks centered at approximate −0.33 V (vs. SCE) in pH 7.0 phosphate buffer solution. It reflects the characteristic of Hb heme Fe(III)/Fe(II) redox couple with fast heterogeneous electron transfer rate. The Hb incorporated into CNx nanotube films exhibited good bioelectrocatalytic activities for the reduction of hydrogen peroxide and nitrite. The results demonstrate that the CNx nanotubes may improve the protein loading with the retention of bioactivity and promote the direct electron transfer greatly. It can be attributed to the existence of a large amount of active sites on the surface of CNx nanotubes and a suitable biocompatible C-N microenvironment introduced by nitrogen doping.