Modified magnesium phosphate cement composed of hyaluronic acid and ultrasound-responsive nanocapsules with improved physicochemical and osteogenic properties

Although magnesium phosphate cement (MPC) has good biocompatibility and degradability, its poor compressive strength and insufficient osteogenic capacity hamper clinical applications. In this study, ultrasound-responsive drug-loading nanocapsules composed of melatonin-containing mesoporous silica and a layer of Pluronic F127 and hyaluronic acid (HA) are incorporated into the cement to enhance the mechanical and biological properties. The melatonin release rate, which can be controlled by the ultrasound intensity and time, reaches 72.45 ± 1.57 % after 7 days at 2 W/cm 2 . The simulated drug release may be based on reversible cleavage and polymerization of F127 under the cavitation effect of ultrasound. The modified cement exhibits a lower reaction temperature (31.41 ± 0.79 °C), longer solidification time (11.9 ± 0.78 min), higher compressive strength (30.19 ± 0.78 MPa), better injectability (90.36 ± 4.01 %), and improved degradation characteristics than the pure MPC due to the complexation effect and adsorption action of HA during hydration. In vitro experiments confirm the excellent antibacterial properties, cytocompatibility, as well as osteogenic capacity. The results reveal an effective strategy to develop multifunctional cement for orthopedic applications.