Interfacial Engineering of Hierarchical Transition Metal Oxide Heterostructures for Highly Sensitive Sensing of Hydrogen Peroxide.

Hydrogen peroxide (H2 O2 ) is a major messenger molecule in cellular signal transduction. Direct detection of H2 O2 in complex environments provides the capability to illuminate its various biological functions. With this in mind, a novel electrochemical approach is here proposed by integrating a series of CoO nanostructures on CuO backbone at electrode interfaces. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction, and X-ray photoelectron spectroscopy demonstrate successful formation of core-shell CuO-CoO hetero-nanostructures. Theoretical calculations further confirm energy-favorable adsorption of H2 O2 on surface sites of CuO-CoO heterostructures. Contributing to the efficient electron transfer path and enhanced capture of H2 O2 in the unique leaf-like CuO-CoO hierarchical 3D interface, an optimal biosensor-based CuO-CoO-2.5 h electrode exhibits an ultrahigh sensitivity (6349 µA m m-1 cm-2 ), excellent selectivity, and a wide detection range for H2 O2 , and is capable of monitoring endogenous H2 O2 derived from human lung carcinoma cells A549. The synergistic effects for enhanced H2 O2 adsorption in integrated CuO-CoO nanostructures and performance of the sensor suggest a potential for exploring pathological and physiological roles of reactive oxygen species like H2 O2 in biological systems.