Hydrogen peroxide (H2O2) is an eminent biomarker in pathogenesis; a selective, highly sensitive real-time detection of H2O2 released from live cells has drawn a significant research interest in bioanalytical chemistry. Binary transition-metal oxides (BTMOs) displayed a recognizable benefit in enhancing the sensitivity of H2O2 detection; although the reported BTMO-based H2O2 sensor's detection limit is still insufficient, it is not appropriate for in situ profiling of trace amounts of cellular H2O2. In this paper, we describe an efficient, reliable electrochemical biosensor based on Mn2CuO4 (MCO) microspheres to assay cellular H2O2. The Mn2CuO4 microspheres were prepared through a superficial solvothermal method. It is obvious from impedance studies, introduction of manganese into copper oxide lattice significantly improved the ionic conductivity, which is beneficial for the electrochemical sensing process. Thanks to the distinct microsphere structure and excellent synergy, MCO-modified electrode exhibited excellent nonenzymatic electrochemical behavior toward H2O2 sensing. The MCO-modified electrode delivered a broad working range (36 nM to 9.3 mM) and an appreciable detection limit (13 nM), with high selectivity toward H2O2. To prove its practicality, the developed sensor was applied in the detection of cellular H2O2 released by RAW 264.7 cells in presence of CHAPS. These results label the possible appliance of the sensor in clinical analysis and pathophysiology. Thus, BTMOs are evolving as a promising candidate in designing catalytic matrices for biosensor applications.
Keywords: H2O2; electrocatalysis; electrochemical sensor; manganese copper oxide; reactive oxygen species (ROS).