Zn-doped MnO2 nanocoating with enhanced catalase-mimetic activity and cytocompatibility protects pre-osteoblasts against H2O2-induced oxidative stress.

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.