Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol-gel film

Hemoglobin (Hb) was entrapped in a titania sol-gel matrix and used as a mimetic peroxidase to construct a novel amperometric biosensor for hydrogen peroxide. The Hb entrapped titania sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process for protein immobilization. The morphologies of both titania sol-gel and the Hb films were characterized using scanning electron microscopy (SEM) and proved to be chemically clean, porous, homogeneous. This matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped Hb and a very low mass transport barrier to the substrates. H2O2 could be reduced by the catalysis of the entrapped hemoglobin at -300 mV without any mediator. The reagentless H2O2 sensor exhibited a fast response (less than 5 s) and sensitivity as high as 1.29 mA mM-1 cm-2. The linear range for H2O2 determination was from 5.0x10-7 to 5.4x10-5 M with a detection limit of 1.2x10-7 M. The apparent Michaelis-Menten constant of the encapsulated hemoglobin was calculated to be 0.18±0.02 mM. The stability of the biosensor was also evaluated