Direct electrochemistry of hemoglobin immobilized on carhon-coated iron nanoparticles for amperometric detection of hydrogen peroxide

A novel method for preparation of hydrogen peroxide biosensor was presented based on immobilization of hemoglobin (Hb) on carbon-coated iron nanoparticles (CIN). CIN was firstly dispersed in a chitosan solution and cast onto a glassy carbon electrode to form a CIN/chitosan composite film modified electrode. Hb was then immobilized onto the composite film with the cross-linking of glutaraldehyde. The immobilized Hb displayed a pair of stable and quasireversible redox peaks and excellent electrocatalytic reduction of hydrogen peroxide (H2O2), which leading to an unmediated biosensor for H2O2. The electrocatalytic response exhibited a linear dependence on H2O2 concentration in a wide range from 3.1 mu M to 4.0 mM with a detection limit of 1.2 mu M (S/N = 3). The designed biosensor exhibited acceptable stability, long-term life and good reproducibility.