Sonochemical synthesis of magnetic core–shell Fe3O4@ZrO2 nanoparticles and their application to the highly effective immobilization of myoglobin for direct electrochemistry

In this study, bifunctional Fe3O4@ZrO2 magnetic core–shell nanoparticles (NPs), synthesized by a simple and effective sonochemical approach, were attached to the surface of a magnetic glassy carbon electrode (MGCE) and successfully applied to the immobilization/adsorption of myoglobin (Mb) for constructing a novel biosensor platform. With the advantages of the magnetism and the excellent biocompatibility of the Fe3O4@ZrO2 NPs, Mb could be easily immobilized on the surface of the electrode in the present of external magnetic field and well retained its bioactivity, hence dramatically facilitated direct electron transfer of Mb was demonstrated. The proposed Mb/Fe3O4@ZrO2 biofilm electrode exhibited excellent electrocatalytic behaviors towards the reduction of H2O2 with a linear range from 0.64 μM to 148 μM. This presented system avoids the complex synthesis for protecting Fe3O4 NPs, supplies a simple, effective and inexpensive way to immobilize protein, and is promising for construction of third-generation biosensors and other bio-magnetic induction devices.

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► Magnetic core–shell Fe3O4@ZrO2 nanoparticle was synthesized by sonochemical approach.
► Fe3O4@ZrO2 NPs provided high capacity for trapping Mb on magnetic glassy carbon electrode surface.
► The constructed Mb/Fe3O4@ZrO2 film exhibited excellent electrocatalytic ability for the reduction of H2O2.
► The proposed method simplifies the immobilization methodology of proteins.