A comprehensive review of manganese dioxide nanoparticles and strategy to overcome toxicity

Chemical and biological methods are available for synthesizing manganese dioxide nanoparticles, with the characteristic electrochemical features tunable through natural product extract. MnO2 nanoparticles reduce the prevalence of organism resistance to drugs. Manganese dioxide nanoparticles are effective against various bacteria, including Staphylococcus aureus and E. coli. Manganese dioxide nanoparticles can potentially be used in the treatment of osteoarthritis and the preservation of cartilage. They are also promising ROS scavengers and may be used to fabricate antioxidant polymer microreactors. In cancer treatment, the MnO2 nanoparticles inhibit ATP production by cancer cells. In magnetic resonance imaging, the nanoparticles improve the signal-to-noise ratio and selectivity. Based on this background information, MnO2 nanoparticles today find use in photodynamic, chemodynamic, and immune therapy and diagnostics, where the oxygen produced by MnO2 nanoparticles is said to improve the therapeutic efficiency. Hybrid nanoparticles of gold nanorods and MnO2 nanoparticles enhance the performance in hormone-, pH-, and NIR- responsiveness. Other applications include glucose oxidase activity, photothermal conversion, and enhanced antitumor immunity. On the other hand, the nanoparticles can cause spermatogenesis failure, oxidative stress, active oxygen, and sperm motility reduction. As surface functionalization can improve the overall functional properties of the nanoparticles, polymer coating on MnO2 nanoparticles brings about new and improved properties. For instance, the layer of biopolymers such as chitosan enhances the magnetic resonance images' quality and opens up the potential for attaching drugs and targeting moieties.