Advances in metal–organic framework-based nanozymes and their applications

Nanozymes bridge the fields of inorganic nanomaterials and biology and have attracted wide attention. Nanozymes have the catalytic capabilities of inorganic materials at the nanoscale, and, thus, the potential to replace natural enzymes. As porous organic–inorganic coordination materials, metal–organic frameworks (MOFs) have a large number of active sites and can mimic the properties of natural enzymes. Therefore, MOF-based nanozymes are considered to have excellent potential for biocatalysis. There are four main categories of such nanomaterials: pristine MOFs, modified MOFs, MOFs composited with natural enzymes, and MOF-derived materials. The diversity of species makes MOF-based nanozymes own wide structural variety. Not only that, diverse preparation methods of them have been reported. These nanozymes can also be modulated by macroscopic physical factors such as light, heat, ultrasound, and magnetic fields, which expand their applications. In this paper, the routes to prepare MOF-based nanozymes that simulate the activity of oxidases, peroxidases, catalases, superoxide dismutase, hydrolases, and multi-functional enzymes are reviewed, together with the factors influencing their catalytic activity. In addition, the applications of these nanomaterials are described, particularly those in sensing and medical treatment. Finally, we discuss possible future directions for the development of MOF-based nanozymes.