Fe3O4, also called magnetite, is a naturally occurring mineral and has been widely used in biomedical applications. However, in the past, all the applications were based on its excellent magnetic properties and neglected its catalytic properties. In 2007, we found that Fe3O4 nanoparticles are able to perform intrinsic enzyme-like activities. A specific term, "nanozyme", is used to describe the new property of intrinsic enzymatic activity of nanomaterials. Since then, Fe3O4 nanoparticles have been used as enzyme mimics, which broadens their applications beyond simply their magnetic properties, with applications in biomedical diagnosis and therapy, environmental monitoring and treatment, the food industry and chemical synthesis. In this chapter, we will summarize the basic features of Fe3O4 as an enzyme mimetic and its applications in biomedicine.
Keywords: Biomedical application; Enzyme mimetic; Enzyme-like activity; Fe3O4; Nanozymes.