Nanozyme antioxidants as emerging alternatives for natural antioxidants: Achievements and challenges in perspective

Nanozymes are nanoparticulated structures with the inherent enzymatic activities, which their advances in bio/nanomedicine field are progressively growing regarding their exceptional properties, such as nano-size, irregular shape, rich surface chemistry, low cost production, etc. These features enable nanostructures to mimic the cellular antioxidant enzymes as novel candidates for treatment of oxidative stress-induced disorders. Oxidative stress reflects principally an imbalance between generation of reactive oxygen species (ROS), such as hydroxyl and superoxide radicals, and the level of antioxidant defense system, so that this imbalance can lead to harsh pathological conditions. Here we present prevalent nanozyme antioxidants as well as their therapeutic concerns from diverse points of view including bio/cytocompatibility and cellular uptake, biomolecular corona, effect of pH and temperature on enzymatic function, and in vivo analysis, which are of paramount importance for reducing the bench-to-clinic gap. (C) 2019 Elsevier Ltd. All rights reserved.