Design synthesis of polypyrrole–Co3O4 hybrid material for the direct electrochemistry of Hemoglobin and Glucose Oxidase

• A novel material Ppy-Co3O4 was synthesized by oxidative polymerization of pyrrole.
• Ppy-Co3O4 and IL create a biocompatible platform for the immobilization of Hb/GOD.
• The DET/Hb and GOD are both achieved on the Ppy-Co3O4/IL composite films.

We designed and synthesized a novel organic–inorganic hybrid material polypyrrole–Co3O4 (Ppy–Co3O4), then mixed it with ionic liquid (IL) to form stable composite films for the immobilization of Hemoglobin (Hb) and Glucose Oxidase (GOD). The combination of Ppy and Co3O4 as well as IL created a platform with exceptional characteristics, and the content of Ppy had an effect on the direct electron transfer (DET) of Hb/GOD. Notably, when weight percentage of pyrrole monomer was 20%, the heterogenous electron transfer rate constant (ks) for Hb and GOD was estimated to be 1.71 s− 1 and 1.67 s− 1, respectively. In the meantime, electrochemical and spectroscopic measurements showed that Hb/GOD remained their bioactivity, and achieved fast electron transfer on the Ppy–Co3O4/IL composite film modified electrode. Furthermore, the Ppy–Co3O4/IL/Hb composite film modified electrode was used as a biosensor, and exhibited a long linear range and lower detection limit to H2O2. The apparent Michaelis–Menten constant (Km) was found to be 0.53 mM. The sensing design based on the Ppy–Co3O4 hybrid material was demonstrated to be effective and promising in developing protein and enzyme biosensors.

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