Oxygen Vacancy Engineering of FeO toward Oxygen-Tolerant Hydrogen Peroxide Reduction for Reliable Bioassays

The accurate determination of hydrogen peroxide (H₂O₂), an important clinical disease relevant biomarker, is of great importance for the diagnosis and management of illnesses. By using the cathodic monitoring approach, H₂O₂ can be accurately detected because interfering signals from easily oxidizable endogenous and exogenous species in biofluids can be avoided. However, the simultaneous occurrence of the oxygen reduction reaction (ORR) restricts the practical use of this cathodic method. In this study, via oxygen vacancy modulation, we synthesized FeO catalysts that can selectively reduce H₂O₂ over O₂. The H₂O₂ detection system based on this catalyst exhibits an outstanding ORR inhibition ability. Furthermore, by integrating this catalyst with glucose oxidase, a model enzyme, a reliable bioassay system was developed that can selectively detect glucose over a wide variety of interferents in artificially simulated tissue fluids. The bioassay system employing this catalyst in conjunction with oxidases is generally applicable to accurate detect a wide range of biomarkers.