"Nanozymes" without catalytic activity should be renamed

Michel Nguyen (1) , Anne Robert (1) , Bernard Meunier (1)

1 LCC - Laboratoire de chimie de coordination

In the aftermath of the report by L. Gao, et al. (Nature Nanotechnol. 2007, 2, 577-583), ferromagnetic nanoparticles such as magnetite are considered by many authors as having an "intrinsic peroxidase-like activity" in the presence of hydrogen peroxide. These authors consequently suggest the discovery of efficient biomimetic oxidation catalysts in the rapidly expanding world of nanomaterials. However, we demonstrate that such nanoparticles have no catalytic activity, the oxidation of the substrate 3,3',5,5'-tetramethylbenzidine being far below one "catalytic cycle" with respect to iron nanoparticles. They are also unable to perform the two-electron oxidation typically catalyzed by a peroxidase, when using a specific peroxidase substrate such as the anticancer drug 9-hydroxy-N2-methylellipticinium, a p-aminophenol derivative known to produce a specific quinone-imine when oxidize by peroxidases. In these conditions, the marginal oxidation reactions observed with magnetite in the presence of hydrogen peroxide are likely due to a Fenton reaction triggered by adventitious metal impurities. The name "nanozyme" is based on a corrupted Michaelis-Menten analysis of these non-catalytic reactions. This erroneous presentation of experimental data is a misconducted research work associated to a semantic falsification. The misleading name "nanozyme" should therefore be replaced by "nano-oxidant" until future nanoparticles having accurate catalytic activities should be named nanozymes.

Mots clés: Catalytic oxidation; Fenton reaction; Magnetite; Nanozymes; Peroxidase

Domaines: Chimie de coordination

Michel Nguyen, Anne Robert, Bernard Meunier. "Nanozymes" without catalytic activity should be renamed. 2021. ⟨hal-03290323⟩