Crosslinked Poly(methyl Methacrylate) Bone Cement Reinforced with a Bioactive Calcium–Olsalazine Metal–Organic Framework

The applications of polymethyl methacrylate (PMMA) bone cement (BC) in orthopedic surgeries have exhibited two major drawbacks: inferior mechanical properties and inferior bioactivities. Herein, we describe the introduction of Ca–olsalazine metal–organic framework (MOF) materials to advance PMMA BC for the first time. The Ca–olsalazine MOFs could be directly grown on the surfaces of PMMA beads via a hydrothermal approach, and then after the double-phase polymerization reaction of PMMA, they were facilely incorporated into the PMMA BCs. Furthermore, with the Ca–olsalazine MOFs offering the amine group to react with citric acid, the amido bonding-induced crosslinking could form during the BC formation process. These treatments remarkably enhanced the mechanical properties of the PMMA BCs, including the flexural strength from 136 to 192 MPa (41.1% increase) and the compression strength from 77 to 99 MPa (28.6% increase). Moreover, the resultant crosslinked Ca–olsalazine MOF- PMMA (c/Ca-MOF/PMMA) BCs induced the deposition of apatite via immersion in simulated body fluid (SBF). In addition, the c/Ca-MOF/PMMA BCs had good cytocompatibility, evaluated using NIH3T3 cells as model cells. Finally, the c/Ca-MOF/PMMA BCs were implanted subcutaneously inside SD mice for three weeks. The obtained results revealed the promotion of the host repair response. This study shows the promising potential of Ca–olsalazine bioactive MOFs in developing high-performance PMMA based BCs.