Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol–gel film Original Research Article

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 5.0×10−7 to 5.4×10−5 M with a detection limit of 1.2×10−7 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.