Immobilization of hemoglobin on MnCO sphere-loaded Au nanoparticles as highly efficient sensing platform towards hydrogen peroxide.

In this paper, we report the synthesis of MnCO-Au hybrid microspheres and their application on the electrochemical biosensing of hydrogen peroxide (HO) based on the immobilization of hemoglobin (Hb). The characterization of MnCO-Au microspheres revealed that an abundance of Au nanoparticles (AuNPs) has been absorbed on the surface of the spherical MnCO by the electrostatic assembly. The combined unique properties of MnCO-Au microspheres are beneficial for the realization of the direct electron transfer of Hb. Hb immobilized on the microspheres maintained its biological activity, showing a surface-controlled process with the heterogeneous electron transfer rate constant (k ) of 2.63 s. The fabricated biosensor displayed an excellent performance for the electrocatalytic reduction of HO. The linear range for the determination of HO was from 0.06-40.0 μM with a detection limit of 0.015 µM (S/N = 3). The biosensor also exhibited high selectivity, good repeatability and long-term stability, which offers great potential for HO detection in real sample analysis.