Highly sensitive and robust peroxidase-like activity of porous nanorods of ceria and their application for breast cancer detection

Porous nanorods of ceria (PN-Ceria), a novel ceria nanostructure with a large surface area and a high surface Ce3+ fraction, exhibited strong intrinsic peroxidase activity toward a classical peroxidase substrate in the presence of H2O2. Peroxidase-like activity of ceria originated from surface Ce3+ species as the catalytic center, thereby explaining the high performance of PN-Ceria as an artificial enzyme mimicking peroxidase. Compared with the natural enzyme horseradish peroxidase (HRP), PN-Ceria showed several advantages such as low cost, easy storage, high sensitivity, and, prominently, chemical and catalytic stability under harsh conditions. Importantly, the enzymatic activity of PN-Ceria remained nearly constant and stable over a wide range of temperature and pH values, ensuring the accuracy and reliability of measurements of its peroxidase-like activity. A PN-Ceria based novel diagnostic system was developed for breast cancer detection with a higher sensitivity than the standard HRP detection system. Our work has laid a solid foundation for the development of PN-Ceria as a novel diagnostic tool for clinical use.