Abstract We reported on a highly sensitive electrochemical biosensor that was fabricated by immobilizing hemoglobin (Hb) onto the surface of a glassy carbon electrode (GCE) modified with a nanocomposite made from polypyrrole@ poly (styrene-alt-maleic anhydride) grafted with 4-aminobenzenesulfonate. Cyclic voltammograms of the modified GCE at pH 7 exhibited a pair of well-defined redox peaks, thus attesting the direct electron transfer from Hb to the electrode. The biosensor can be used to determine H 2 O 2 and, if operated at a
