Synthesis of Mesoporous CuO Hollow Sphere Nanozyme for Paper-Based Hydrogen Peroxide Sensor

Point-of-care monitoring of hydrogen peroxide is important due to its wide usage in biomedicine, the household and industry. Herein, a paper sensor is developed for sensitive, visual and selective detection of H₂O₂ using a mesoporous metal oxide hollow sphere as a nanozyme. The mesoporous CuO hollow sphere is synthesized by direct decomposition of copper-polyphenol colloidal spheres. The obtained mesoporous CuO hollow sphere shows a large specific surface area (58.77 m²/g), pore volume (0.56 cm³/g), accessible mesopores (5.8 nm), a hollow structure and a uniform diameter (~100 nm). Furthermore, they are proven to show excellent peroxidase-like activities with K_m and V_max values of 120 mM and 1.396 × 10^-5 M·s^-1, respectively. Such mesoporous CuO hollow spheres are then loaded on the low-cost and disposable filter paper test strip. The obtained paper sensor can be effectively used for detection of H₂O₂ in the range of 2.4-150 μM. This work provides a new kind of paper sensor fabricated from a mesoporous metal oxide hollow sphere nanozyme. These sensors could be potentially used in bioanalysis, food security and environmental protection.