A hydrogen peroxide biosensor based on direct electrochemistry of hemoglobin in Hb–Ag sol films

Hemoglobin (Hb) was used as a template to fabricate hemoglobin–silver (Hb–Ag) sol in which the hemoglobin showed direct electrochemistry on a glass carbon (GC) electrode. Ultraviolet–visible (UV–vis) spectra and reflectance absorption infrared (RAIR) spectra suggested that hemoglobin in Hb–Ag sol retained its native secondary structure. Scanning electron microscopy (SEM) demonstrated that the morphology of the Hb film was much different from the Hb–Ag sol film. The Hb–Ag film proved to exhibit a good electrocatalytic activity for the reduction of hydrogen peroxide. Based on this, a novel amperometric hydrogen peroxide biosensor was developed, which showed a sensitive response to the reduction of H2O2 without any electron mediator. Under optimum conditions, the biosensor responded linearly to H2O2 in the concentration range of 1 × 10−6 to 2.5 × 10−2 M with detection limit of 1 × 10−7 M at 3σ. Moreover, the studied biosensor exhibited high sensibility, good reproducibility, and long-term stability.