Advances in the application of manganese dioxide and its composites for theranostics

Manganese dioxide (MnO2), a type of redox-active transition-metal dioxide, has found wide applications in catalysts, oxidants, ferrites, achromats and battery materials. In addition, MnO2 is also increasingly being used in the biomedical field for disease diagnosis and treatment. Despite its great potential, there are limited articles that comprehensively review the use of MnO2 in disease diagnosis and treatment. This review provides a concise overview of the latest developments in MnO2 nanomaterials, focusing on their applications as magnetic resonance, photoacoustic and fluorescent contrast agents. We first summarize the preparation methods of MnO2 nanomaterials and the mechanisms by which they serve as magnetic resonance contrast agents. We then briefly introduce their applications as photoacoustic and fluorescent contrast agents. Finally, we provide an overview of the therapeutic applications of MnO2 nanomaterials and discuss the challenges and prospects for their future clinical applications.