Hydrogen peroxide biosensor based on myoglobin/colloidal gold nanoparticles immobilized on glassy carbon electrode by a Nafion film

A novel amperometric sensor of hydrogen peroxide was developed based on the immobilization of myoglobin (Mb) and colloidal gold nanoparticles (CGNs) on a glassy carbon electrode (GCE) by a Nafion film. The immobilized Mb displayed a pair of well-defined and nearly reversible cyclic voltammetric peaks with a formal potential (E°′) of −0.373 V in a 0.1 M phosphate buffer solution (PBS) of pH 6.9. The formal potential of the Mb heme Fe(III)/Fe(II) couple shifted linearly with pH with a slope of −49.6 mV/pH, indicating that the electron transfer is accompanied by single-proton transportation. The immobilized Mb exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide, based on which an unmediated biosensor for hydrogen peroxide was achieved. The linear range for determination of hydrogen peroxide was from 1.5 × 10−6 to 9.0 × 10−5 M with a detection limit of 5.0 × 10−7 M at a signal-to-noise ratio of 3. The stability, repeatability and selectivity of the biosensor were also evaluated.