Analyzing Dual Behavior of Metallic Nanozymes on Protein Protection and Oxidation

Nanozymes (NZs) have emerged as a powerful tool in several biomedical and biotechnology fields, driven by their stability, tunability, and wide operational range. Metallic nanozymes can present multiple competing antioxidant and pro-oxidative enzyme-like properties and thus have been shown to have protective or degrading actions, depending on the material composition and the biological/chemical environment, opening the possibility for different applications. To clarify the potential impact of peroxidase (POD)-like activity on proteins, here we tested the activity of metal NZs toward different protein substrates. We observed that, under typical biological (physiological and pathological) levels of H2O2, there is no detectable protein alteration induced, while at higher H2O2 concentrations, AuNZ POD-like behavior can cause significant changes to the native state of proteins, disrupting their original structure and modifying their charge distribution. Comparing the effect of AuNZs with other noble metal NZs (PtNZs and PdNZs) by using a combination of spectroscopic and electrophoresis techniques, we found that PtNZs and PdNZs tend to instead preferentially perform a protective action via catalase (CAT)-like reaction, even under harsh H2O2 conditions.