Multi-functional oxidase-like activity of praseodymia nanorods and nanoparticles.

[Display omitted] • Synthesis of praseodymia nanorods and nanoparticles. • Excellent multi-funtional oxidase-like activities of praseodymia nanomaterials. • Colorimetric sensing of L-cysteine and fluoride using praseodymia nanorods. The ability to mimic protein-based oxidase with multi-functional inorganic nanozymes would greatly advance biomedical and clinical practices. Praseodymia (PrO x) nanorods (NRs) and nanoparticles (NPs) have been synthesized using hydrothermal and precipitation methods. Both PrO x catalysts with different morphologies exhibit significantly higher oxidase-like activities (Michaelis-Menten constant K m ≤ 0.026 mM) than commercial PrO x and most so-far-reported artificial enzymes. One of the substrates, dopamine, can be oxidized and further polymerized to generate polydopamine in acidic conditions. Akin to CeO 2 , which is a well-studied nanozyme, a different mechanism involving holes+, oxygen vacancies and oxygen mobility over PrO x catalysts has been proposed in this work. However, fluoride ions were found to impose opposite effects on the oxidase-mimicking activity of PrO x and CeO 2 , implying a promising path for the exploration of new nanozymes. In support of this, PrO x was further applied in colorimetric sensing of L-cysteine and fluoride with high sensitivity. [ABSTRACT FROM AUTHOR]