A hydrogen peroxide biosensor based on direct electrochemistry of hemoglobin incorporated in PEO–PPO–PEO triblock copolymer film

A new film of triblock copolymer EO20PO70EO20 (P123) was used to incorporate hemoglobin (Hb) onto the surface of pyrolytic graphite (PG) electrode for biosensor fabrication. UV–vis spectra suggested that Hb in the film could keep its native secondary structure. A pair of stable, well-defined and quasi-reversible cyclic voltammetric peaks was observed with the formal potential of about −0.29 V (vs. SCE) at the Hb/P123 film-modified electrode in pH 6.0 NaAc–HAc buffer solution, characteristic of heme FeIII/FeII redox couple of Hb. The modified electrode exhibited good electrocatalytic activity to the reduction of hydrogen peroxide (H2O2). The linear concentration range of the unmediated H2O2 biosensor was from 1.0 × 10−6 to 5.0 × 10−4 M with a detection limit of 5.0 × 10−7 M. The apparent Michaelis–Menten constant of Hb in the P123 film was estimated to be 0.51 mM, showing its high affinity. The stability, reproducibility and selectivity of the biosensor were also evaluated.