Kinetic\nProfiling of Oxidoreductase-Mimicking Nanozymes:\nImpact of Multiple Activities, Chemical Transformations, and Colloidal\nStability

In\ncontrast to homogeneous enzyme catalysis, nanozymes are nanosized\nheterogeneous catalysts that perform reactions on a rigid surface.\nThis fundamental difference between enzymes and nanozymes is often\noverlooked in kinetic studies and practical applications. In this\narticle, using 14 nanozymes of various compositions (core@shell, metal–organic\nframeworks, metal, and metal oxide nanoparticles), we systematically\ndemonstrate that nontypical features of nanozymes, such as multiple\ncatalytic activities, chemical transformations, and aggregation, need\nto be considered in nanozyme catalysis. Ignoring these features results\nin the inaccurate quantification of catalytic activity. Neglecting\nthe multiple activities led to a six-time underestimation of Mn<sub>2</sub>O<sub>3</sub> oxidation activity and mischaracterization of\nthis material as a low-active peroxidase-mimicking nanozyme. Additionally,\noverlooking chemical stability during catalytic reactions led to the\nreporting of high peroxidase-mimicking activity for Au@Ag nanoparticles,\nwhich, in reality, exhibited no intrinsic activity and oxidized the\nsubstrate through the leakage of Ag<sup>+</sup> ions. Ignoring the\nchemical stability of Au@Prussian Blue nanoparticles may lead to more\nthan four times overestimation of peroxidase-mimicking activity after\njust 24 h of storage. Finally, disregarding the colloidal stability\nof nanozymes led to a five-time inaccuracy in catalytic activity.\nThese findings underscore the necessity of optimizing procedures to\naccount for these factors in nanozyme kinetic measurements, which\nwill in turn ensure more reliable biosensors and the success of other\npractical applications.