Facile Synthesis of ZnMn₂O₄@rGO Microspheres for Ultrasensitive Electrochemical Detection of Hydrogen Peroxide from Human Breast Cancer Cells

Mixed transition-metal oxides have witnessed increasing attention in catalysts and electrocatalysts. Herein, reduced graphene oxide-wrapped ZnMn 2 O 4 microspheres (ZnMn 2 O 4 @rGO) were facilely synthesized through the solvothermal technique. The microstructure and morphology of ZnMn 2 O 4 @rGO microspheres were analyzed under Raman, X-ray photoelectron, X-ray diffraction, and energy-dispersive spectroscopies and scanning electron microscopy. The synthesized ZnMn 2 O 4 @rGO was employed as an excellent electrocatalyst for the reduction of hydrogen peroxide (H 2 O 2 ). The ZnMn 2 O 4 @rGO-modified glassy carbon electrode (ZnMn 2 O 4 @rGO/GCE) exhibited a linear detection to H 2 O 2 in a wide concentration range of 0.03–6000 μM with a detection limit of 0.012 μM. The biosensor was evaluated to determine H 2 O 2 secreted by human breast cancer cells (MCF-7), indicating its promising applications in physiology and diagnosis.