Dual-functional coating that inhibits bone resorption and promotes bone formation applied to the surface modification of titanium screws

The purpose of this study was to solve the problem of Ti screw loosening in patients with osteoporosis. Romosozumab (Rom), a bone resorption inhibitor, and bone morphoprotein 2 (BMP-2), an osteogenic growth factor, were encapsulated into TiO2 nanotubes (TNTs) by polydopamine (pDA). The TiO2/Ti materials coated with Rom and BMP-2 were characterized by scanning electron microscopy (SEM), water contact angle (WCA), Fourier transform infrared (FTIR) spectroscopy and CCK-8 assays. Ti screws loaded with Rom and BMP-2 were implanted into the tibia of rats to evaluate their abilities to inhibit bone resorption, promote bone formation and enhance screw mechanical strength by micro-CT and pull-out force tests. The results showed that the loading of Rom in TNT could significantly inhibit bone resorption, while the loading of Rom and BMP-2 could significantly enhance bone formation and screw mechanical ability. The strategy of loading Rom and BMP-2 onto the surface of Ti screws can effectively reduce the risk of screw loosening in patients with osteoporosis.