BSA-Stabilized Gold-Nanozymes Reveal 4-Order Higher Catalytic Efficiency and 2-Fold Higher Substrate Affinity than Mno2-Nanozymes

Abstract

Saeed Reza Hormozi Jangi

In this study, the catalytic efficiency and substrate affinity of BSA-stabilized gold-nanozymes and MnO2 - nanozymes were quantified via kinetics studies. In this regard, BSA-stabilized gold-nanozymes and MnO2 - nanozymes were synthesized by simple and green methods and then characterized by TEM and DLS analysis. Both nanozymes revealed semi-special morphology, however, the BSA-stabilized gold-nanozymes showed a small mean size of 13.0 nm while the MnO2 -nanozymes had a mean size of 100.0 nm. The kinetic studies were carried out using the Michaelis–Menten kinetics model for both BSA-stabilized gold-nanozymes and MnO2 - nanozymes and then the kinetic parameters of nanozymes (Km and Vmax) were estimated using the linear plot of Lineweaver–Burk for both nanozymes. The results exhibited a Vmax of 185 nM sec-1 and 47 nM sec-1 for the BSA- stabilized gold-nanozymes and MnO2 -nanozymes, in order. The ratio of Vmax(gold)/Vmax(MnO2 ) was found to be about 4.0 which pointed that the catalytic efficiency of gold-nanozymes is 4.0-fold higher than the catalytic efficiency of MnO2 - nanozymes. The Km value was found to be 0.72 mM and 1.6 mM for the as-prepared BSA-stabilized gold-nanozymes and MnO2 -nanozymes, respectively. The Km of MnO2 -nanozymes is 2.2-fold higher than that of BSA-stabilized gold-nanozymes, since the Km shows the affinity of substrate for binding to nanozyme active nodes (lower Km=higher affinity), it is consultable that the substrate affinity toward MnO2 - nanozymes is 2.2-fold lower than that of the BSA-stabilized gold-nanozymes. Considering the above results, the as-prepared BSA-stabilized gold nanozymes are very stronger peroxidase-like mimics than the metal oxide MnO2 -nanozymes.

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