A highly efficient and long-lasting agent for reactive oxygen species removal based on biomimetic mineralization of metal–organic frameworks

Organisms rely heavily on enzyme-based antioxidant systems to remove reactive oxygen species (ROS) that are produced in vivo or generated indirectly upon contact with contaminants to prevent themselves from being damaged. However, it is difficult to maintain the stability of the enzyme, and to achieve both the removal and the inhibition of ROS. Herein we report a MOF–enzyme composite that simultaneously encapsulates two antioxidant enzymes with modified ZIF-8 (M-ZIF-8) to achieve efficient and persistent ROS removal. Meanwhile, we choose ZnO as the Zn source of M-ZIF-8, endowing the composite with ultraviolet resistance, which can inhibit the generation of ROS. The superoxide dismutase (SOD) activities of enzyme-M-ZIF-8 were assessed by a modified WST-8 assay. The IC50 value required to yield 50% inhibition of the reduction of WST-8 is 0.3047 μM, demonstrating a better SOD-like activity than most of the SOD mimic products. In addition, our composite showed a ROS removal rate of nearly 50% at room temperature, good activity after high-temperature treatment and prolonged storage, and outstanding UV resistance.