A hydrogen peroxide biosensor based on direct electron transfer from hemoglobin to an electrode modified with Nafion and activated nanocarbon

A biosensor for hydrogen peroxide (HP) was developed by immobilizing hemoglobin on a glassy carbon electrode modified with activated carbon nanoparticles/Nafion. The characteristics of the sensor were studied by UV-vis spectroscopy and electrochemical methods. The immobilized Hb retained its native secondary structure, undergoes direct electron transfer (with a heterogeneous rate constant of 3.37 +/- 0.5 s(-1)), and displays excellent bioelectrocatalytic activity to the reduction of HP. Under the optimal conditions, its amperometric response varies linearly with the concentration of HP in the range from 0.9 mu M to 17 mu M. The detection limit is 0.4 mu M (at S/N = 3). Due to the commercial availability and low cost of activated carbon nanoparticles, it can be considered as a useful supporting material for construction of other third-generation biosensors.