Manganese(IV) oxide, an inorganic compound, is used as a pigment as a reagent in organic synthesis. This compound is also used as a nanoparticle and has different applications. For example, fucoidan-coated manganese dioxide nanoparticles (Fuco-MnO₂-NPs) may potentiate the effects of radiation therapy via dual targeting of tumor hypoxia and angiogenesis and has the great clinical potential in the treatment of hypoxic, radioresistant pancreatic cancer. Multifunctional hyaluronic acid-MnO2 nanoparticles (HA-MnO2 NPs) can be used for sensitive, targeted magnetic resonance imaging detection of gliomas and simultaneous attenuation of tumor hypoxia.