Zn-doped MnO₂ nanocoating with enhanced catalase-mimetic activity and cytocompatibility protects pre-osteoblasts...

Therapeutic application in prevention and treatment of bone diseases, particularly osteoporosis, has recently started to emerge for manganese dioxide (MnO₂) nanoparticles and nanocoatings whereby their antioxidant catalase-mimetic property can be exploited to control oxidative stress by reducing the amount of H₂O₂. Doping is an efficient method to enhance the catalase-mimetic activity of MnO₂, which can potentially ameliorate osteogenesis under oxidative stress. Herein, Zn²⁺ doped MnO₂ (Zn-MnO₂) nanocoating was fabricated on orthopedic titanium implant by a facile UV-photolysis reaction. The Zn-MnO₂ nanocoating showed better cytocompatibility than the MnO₂ nanocoating, as indicated by enhanced cell proliferation, differentiation and mineralization of MC3T3-E1 pre-osteoblasts. This was probably due to the increased surface hydrophilicity as well as the combination effect of released Zn²⁺ and Mn²⁺ from the Zn-MnO₂ nanocoating. Importantly, the Zn-MnO₂ nanocoating with enhanced catalase-like activity exerted greater effects to suppress the intracellular oxidation products generation and prevent the depletion of dismutase superoxide levels under H₂O₂-induced oxidative stress, which in turn protected MC3T3-E1 pre-osteoblast functions. Overall, surface modification of titanium implants with the Zn-MnO₂ nanocoating could be utilized to ameliorate oxidative stress-inhibited osteogenesis.