Novel injectable biomaterials for bone augmentation based on isosorbide dimethacrylic monomers

Current bone cements, especially those based on polymethyl methacrylate (PMMA), face limitations such as high stiffness and possible toxicity from unreacted monomers. These issues can lead to suboptimal clinical outcomes. While prior research has demonstrated the mechanical and biological drawbacks of PMMA, few alternatives have been developed that address both injectability and biocompatibility. The need for a material that mimics bone properties and supports cell viability remains unmet. This gap motivated the development of new monomers derived from renewable sources. These materials aim to reduce elastic modulus and residual toxicity. No prior work had resolved the balance between mechanical performance and biological safety. The search for sustainable and biocompatible alternatives continues to drive innovation in orthopedic biomaterials.

The goal of this research was to develop a novel injectable bone cement using isosorbide-derived dimethacrylic monomers. The aim was to overcome the limitations of conventional PMMA-based cements. The study focused on creating a low-viscosity, bioactive formulation suitable for bone augmentation. By using renewable resources, the researchers sought to improve both biocompatibility and mechanical properties. The specific problem addressed was the excessive stiffness and potential toxicity of traditional bone cements. The motivation stemmed from the need for a material that could be safely injected and set within a clinically relevant timeframe. The team aimed to synthesize and evaluate two new monomers for their suitability in bone cement applications. The ultimate goal was to present a viable alternative to PMMA-based systems.

The researchers synthesized two novel dimethacrylic monomers: ISDGMA and ISETDMA, both derived from isosorbide. These monomers were used to formulate low-viscosity compositions containing nano-hydroxyapatite. The materials were prepared as a two-paste system to facilitate handling and injection. Rheological tests were conducted to assess shear-thinning behavior and setting times. Mechanical properties, including Young’s modulus, were measured after curing. Water absorption was evaluated to determine hydrophilicity and its effect on modulus. Cell viability was tested using mice fibroblasts (BALB/3T3) in an MTT assay. Additional testing was performed on human osteosarcoma cells (SaOS-2) using an MTS test. These methods allowed the team to evaluate both the physical and biological performance of the new materials.

The formulations demonstrated non-Newtonian shear-thinning behavior, with setting times ranging from 2.6 to 5.3 minutes at 37°C. Maximum curing temperatures reached up to 65°C, indicating controlled exothermic reactions. The Young’s modulus of the cured material decreased from 1,429 MPa to 470 MPa after water absorption of up to 13.6%. This reduction suggests a closer match to bone properties. Both poly(ISDGMA) and poly(ISETDMA) showed cell viabilities above 70% in the MTT test on BALB/3T3 fibroblasts. The MTS test on SaOS-2 cells revealed concentration-dependent viability, indicating potential for osteoblast compatibility. These findings suggest the materials are biocompatible and suitable for bone augmentation. The results support the use of isosorbide-based monomers as a viable alternative to PMMA.

The study demonstrated that isosorbide-derived dimethacrylic monomers can be used to create injectable bone cements with favorable mechanical and biological properties. The materials exhibited setting times and viscosities suitable for clinical use. The reduced elastic modulus and high water absorption suggest improved bone compatibility. Both monomers showed acceptable cell viability in fibroblast and osteosarcoma cell tests. The results indicate that these materials could overcome some of the limitations of conventional PMMA-based cements. The authors propose that these findings support further development of isosorbide-based bone cements. The study highlights the potential of renewable resources in biomaterial design. These conclusions are based on the observed mechanical and biological performance of the new formulations.