Enhanced compressive strength and biocompatibility of porous PVA_f/MPC composite scaffolds featuring directional lamellar pore channels

Magnesium phosphate bone cement (MPC) is one of the most important candidates for bone implant materials due to its properties such as no need for sintering, self-curing formation, high early compressive strength and rapid degradation. However, traditional methods for creating porous structures for MPC, such as foaming or incorporating degradable materials, often result in closed pores or pores predominantly localized on the surface, severely limiting its comprehensive degradation and effective formation of new bone. In this study, porous MPC scaffolds with directional layered channels were successfully prepared using innovative directional freeze-drying and in situ hydration techniques. The key findings of the study were that the incorporation of degradable acidic PVA staple fibers not only significantly improved the mechanical properties of the porous MPC scaffolds, but also effectively addressed the issue of high alkaline cell toxicity upon degradation. When the fiber content is 3 wt%, the compressive strength of the porous scaffold increases from 4.67 to 8.83 MPa, which was attributed to both the high tensile strength displayed by PVA fibers and the presence of multiple fiber forms within the scaffold. And the acidification of PVA fibers during degradation resulting in a decrease in the pH value of the SBF from 8.93 to 7.67, which reduced the cytotoxicity of the scaffolds. Furthermore, through a 7-day microzone in situ hydration process, the porous MPC scaffold with a Mg/P molar ratio of 1.45:1 transformed into KMgPO₄·6H₂O. The pH value of simulated body fluid (SBF) showed an increasing trend with the rising Mg/P molar ratio following degradation of porous MPC scaffolds. The conclusions of the study showed that the prepared porous PVA_f/MPC scaffolds with oriented hierarchical channels exhibit non-cytotoxicity and provide an optimal environment for cell survival and proliferation, and demonstrated great potential applications in the field of biodegradable bone implantation materials.